Alkali/Transition Metal Halo-And Hydroxy-Phosphates And Related Electrode Active Materials

ABSTRACT

The invention provides a novel polyanion-based electrode active material for use in a secondary or rechargeable electrochemical cell, wherein the electrode active material is represented by the general formula A a M b (XY 4 ) 2 Z d .

RELATED ELECTRODE ACTIVE MATERIALS

This application is a continuation of U.S. patent application Ser. No.10/870,135 filed Jun. 16, 2004, allowed, which is a divisional of U.S.patent application Ser. No. 10/014,822, filed Oct. 26, 2001, issued asU.S. Pat. No. 6,777,132, which is a continuation-in-part of U.S. patentapplication Ser. No. 09/559,861, filed Apr. 27, 2000, issued as U.S.Pat. No. 6,387,568.

FIELD OF THE INVENTION

This invention relates to electrode active materials, electrodes, andbatteries. In particular, this invention relates to active materialscomprising lithium or other alkali metals, transition metals, phosphatesor similar moieties, and halogen or hydroxyl moieties.

BACKGROUND OF THE INVENTION

A wide variety of electrochemical cells, or “batteries,” are known inthe art. In general, batteries are devices that convert chemical energyinto electrical energy, by means of an electrochemicaloxidation-reduction reaction. Batteries are used in a wide variety ofapplications, particularly as a power source for devices that cannotpracticably be powered by centralized power generation sources (e.g., bycommercial power plants using utility transmission lines).

Batteries can be generally described as comprising three components: ananode, that contains a material that is oxidized (yields electrons)during discharge of the battery (i.e., while it is providing power); acathode that contains a material that is reduced (accepts electrons)during discharge of the battery; and an electrolyte that provides fortransfer of ions between the cathode and anode. During discharge, theanode is the negative pole of the battery, and the cathode is thepositive pole. Batteries can be more specifically characterized by thespecific materials that make up each of these three components.Selection of these components can yield batteries having specificvoltage and discharge characteristics that can be optimized forparticular applications.

Batteries can also be generally categorized as being “primary,” wherethe electrochemical reaction is essentially irreversible, so that thebattery becomes unusable once discharged; and “secondary,” where theelectrochemical reaction is, at least in part, reversible so that thebattery can be “recharged” and used more than once. Secondary batteriesare increasingly used in many applications, because of their convenience(particularly in applications where replacing batteries can bedifficult), reduced cost (by reducing the need for replacement), andenvironmental benefits (by reducing the waste from battery disposal).

There are a variety of secondary battery systems known in the art. Amongthe most common systems are lead-acid, nickel-cadmium, nickel-zinc,nickel-iron, silver oxide, nickel metal hydride, rechargeablezinc-manganese dioxide, zinc-bromide, metal-air, and lithium batteries.Systems containing lithium and sodium afford many potential benefits,because these metals are light in weight, while possessing high standardpotentials. For a variety of reasons, lithium batteries are, inparticular, commercially attractive because of their high energydensity, higher cell voltages, and long shelf-life.

Lithium batteries are prepared from one or more lithium electrochemicalcells containing electrochemically active (electroactive) materials.Among such batteries are those having metallic lithium anodes and metalchalcogenide (oxide) cathodes, typically referred to as “lithium metal”batteries. The electrolyte typically comprises a salt of lithiumdissolved in one or more solvents, typically nonaqueous aprotic organicsolvents. Other electrolytes are solid electrolytes (typically polymericmatrixes) that contain an ionic conductive medium (typically a lithiumcontaining salt dissolved in organic solvents) in combination with apolymer that itself may be tonically conductive but electricallyinsulating.

Cells having a metallic lithium anode and metal chalcogenide cathode arecharged in an initial condition. During discharge, lithium metal yieldselectrons to an external electrical circuit at the anode. Positivelycharged ions are created that pass through the electrolyte to theelectrochemically active (electroactive) material of the cathode. Theelectrons from the anode pass through the external circuit, powering thedevice, and return to the cathode.

Another lithium battery uses an “insertion anode” rather than lithiummetal, and is typically referred to as a “lithium ion” battery.Insertion or “intercalation” electrodes contain materials having alattice structure into which an ion can be inserted and subsequentlyextracted. Rather than chemically altering the intercalation material,the ions slightly expand the internal lattice lengths of the compoundwithout extensive bond breakage or atomic reorganization. Insertionanodes contain, for example, lithium metal chalcogenide, lithium metaloxide, or carbon materials such as coke and graphite. These negativeelectrodes are used with lithium-containing insertion cathodes. In theirinitial condition, the cells are not charged, since the anode does notcontain a source of cations. Thus, before use, such cells must becharged in order to transfer cations (lithium) to the anode from thecathode. During discharge the lithium is then transferred from the anodeback to the cathode. During subsequent recharge, the lithium is againtransferred back to the anode where it reinserts. This back-and-forthtransport of lithium ions (Li⁺) between the anode and cathode duringcharge and discharge cycles had led to these cells as being called“rocking chair” batteries.

A variety of materials have been suggested for use as cathode activematerials in lithium batteries. Such materials include, for example,MoS₂, MnO₂, TiS₂, NbSe₃, LiCoO₂, LiNiO₂, LiMn₂O₄, V₆O₁₃, V₂O₅, SO₂,CuCl₂. Transition metal oxides, such as those of the general formulaLi_(x)MO_(y), are among those materials preferred in such batterieshaving intercalation electrodes. Other materials include lithiumtransition metal phosphates, such as LiFePO₄, and Li₃V(PO₄)₃. Suchmaterials having structures similar to olivine or NASICON materials areamong those known in the art. Cathode active materials among those knownin the art are disclosed in S. Hossain, “Rechargeable Lithium Batteries(Ambient Temperature),” Handbook of Batteries, 2d ed., Chapter 36,Mc-Graw Hill (1995); U.S. Pat. No. 4,194,062, Carides, et al., issuedMar. 18, 1980; U.S. Pat. No. 4,464,447, Lazzari, et al., issued Aug. 7,1984; U.S. Pat. No. 5,028,500, Fong et al., issued Jul. 2, 1991; U.S.Pat. No. 5,130,211, Wilkinson, et al., issued Jul. 14, 1992; U.S. Pat.No. 5,418,090, Koksbang et al., issued May 23, 1995; U.S. Pat. No.5,514,490, Chen et al., issued May 7, 1996; U.S. Pat. No. 5,538,814,Kamauchi et al., issued Jul. 23, 1996; U.S. Pat. No. 5,695,893, Arai, etal., issued Dec. 9, 1997; U.S. Pat. No. 5,804,335, Kamauchi, et al.,issued Sep. 8, 1998; U.S. Pat. No. 5,871,866, Barker et al., issued Feb.16, 1999; U.S. Pat. No. 5,910,382, Goodenough, et al., issued Jun. 8,1999; PCT Publication WO/00/31812, Barker, et al., published Jun. 2,2000; PCT Publication WO/00157505, Barker, published Sep. 28, 2000; U.S.Pat. No. 6,136,472, Barker et al., issued Oct. 24, 2000; U.S. Pat. No.6,153,333, Barker, issued Nov. 28, 2000; PCT Publication WO/01/13443,Barker, published Feb. 22, 2001; and PCT Publication WO/01/54212, Barkeret al., published Jul. 26, 2001.

In general, such a cathode material must exhibit a high free energy ofreaction with lithium, be able to intercalate a large quantity oflithium, maintain its lattice structure upon insertion and extraction oflithium, allow rapid diffusion of lithium, afford good electricalconductivity, not be significantly soluble in the electrolyte system ofthe battery, and be readily and economically produced. However, many ofthe cathode materials known in the art lack one or more of thesecharacteristics. As a result, for example, many such materials are noteconomical to produce, afford insufficient voltage, have insufficientcharge capacity, or lose their ability to be recharged over multiplecycles.

SUMMARY OF THE INVENTION

The invention provides electrode active materials comprising lithium orother alkali metals, a transition metal, a phosphate or similar moiety,and a halogen or hydroxyl moiety. Such electrode actives include thoseof the formula:A_(a)M_(b)(XY₄)_(c)Z_(d),

wherein

-   -   (a) A is selected from the group consisting of Li, Na, K, and        mixtures thereof, and 0<a≦8;    -   (b) M comprises one or more metals, comprising at least one        metal which is capable of undergoing oxidation to a higher        valence state, and 1≦b≦3;    -   (c) XY₄ is selected from the group consisting of        X′O_(4-x)Y′_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof,        where X′ is P, As, Sb, Si, Ge, S, and mixtures thereof; X″ is P,        As, Sb, Si, Ge and mixtures thereof; Y′ is halogen; 0≦x<3; and        0<y<4; and 0<c≦3;    -   (d) Z is OH, halogen, or mixtures thereof, and 0<d≦6; and    -   (e) wherein M, X, Y, Z, a, b, c, d, x and y are selected so as        to maintain electroneutrality of said compound.    -   (f) In a preferred embodiment, M comprises two or more        transition metals from Groups 4 to 11 of the Periodic Table. In        another preferred embodiment, M comprises M′M″, where M′ is at        least one transition metal from Groups 4 to 11 of the Periodic        Table; and M″ is at least one element from Groups 2, 3, 12, 13,        or 14 of the Periodic Table. Preferred embodiments include those        where c=1, those where c=2, and those where c=3. Preferred        embodiments include those where a≦1 and c=1, those where a=2 and        c=1, and those where a≧3 and c=3. Preferred embodiments also        include those having a structure similar to the mineral olivine        (herein “olivines”), and those having a structure similar to        NASICON (NA Super Ionic CONductor) materials (herein        “NASICONs”).    -   (g) This invention also provides electrodes comprising an        electrode active material of this invention. Also provided are        batteries that comprise a first electrode having an electrode        active material of this invention; a second electrode having a        compatible active material; and an electrolyte. In a preferred        embodiment, the novel electrode material of this invention is        used as a positive electrode (cathode) active material,        reversibly cycling lithium ions with a compatible negative        electrode (anode) active material.

It has been found that the novel electrode materials, electrodes, andbatteries of this invention afford benefits over such materials anddevices among those known in the art. Such benefits include increasedcapacity, enhanced cycling capability, enhanced reversibility, andreduced costs. Specific benefits and embodiments of the presentinvention are apparent from the detailed description set forth herein.It should be understood, however, that the detailed description andspecific examples, while indicating embodiments among those preferred,are intended for purposes of illustration only and are not intended tolimited the scope of the invention.

DESCRIPTION OF THE INVENTION

The present invention provides electrode active materials for use in abattery. As used herein, “battery” refers to a device comprising one ormore electrochemical cells for the production of electricity. Eachelectrochemical cell comprises an anode, a cathode, and an electrolyte.Two or more electrochemical cells may be combined, or “staked,” so as tocreate a multi-cell battery having a voltage that is the sum of thevoltages of the individual cells.

The electrode active materials of this invention may be used in theanode, the cathode, or both. Preferably, the active materials of thisinvention are used in the cathode. (As used herein, the terms “cathode”and “anode” refer to the electrodes at which oxidation and reductionoccur, respectively, during battery discharge. During charging of thebattery, the sites of oxidation and reduction are reversed. Also, asused herein, the words “preferred” and “preferably” refer to embodimentsof the invention that afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful and is not intended to exclude other embodiments from the scopeof the invention.)

Electrode Active Materials:

The present invention provides active materials (herein “electrodeactive materials”) comprising lithium or other alkali metals, atransition metal, a phosphate or similar moiety, and a halogen orhydroxyl moiety. Such electrode active materials include those of theformula A_(a)M_(b)(XY₄)_(c)Z_(d). (As used herein, the word “include,”and its variants, is intended to be non-limiting, such that recitationof items in a list is not to the exclusion of other like items that mayalso be useful in the materials, compositions, devices, and methods ofthis invention.)

A is selected from the group consisting of Li (lithium), Na (sodium), K(potassium), and mixtures thereof. In a preferred embodiment, A is Li,or a mixture of Li with Na, a mixture of Li with K, or a mixture of Li,Na and K. In another preferred embodiment, A is Na, or a mixture of Nawith K. Preferably “a” is from about 0.1 to about 6, more preferablyfrom about 0.2 to about 6. Where c=1, a is preferably from about 0.1 toabout 3, preferably from about 0.2 to about 2. In a preferredembodiment, where c=1, a is less than about 1. In another preferredembodiment, where c=1, a is about 2. Where c=2, a is preferably fromabout 0.1 to about 6, preferably from about 1 to about 6. Where c=3, ais preferably from about 0.1 to about 6, preferably from about 2 toabout 6, preferably from about 3 to about 6.

M comprises one or more metals, comprising at least one metal which iscapable of undergoing oxidation to a higher valence state. In apreferred embodiment, removal of alkali metal from the electrode activematerial is accompanied by a change in oxidation state of at least oneof the metals comprising M. The amount of said metal that is availablefor oxidation in the electrode active material determines the amount ofalkali metal that may be removed. Such concepts are, in generalapplication, well known in the art, e.g., as disclosed in U.S. Pat. No.4,477,541, Fraioli, issued Oct. 16, 1984; and U.S. Pat. No. 6,136,472,Barker, et al., issued Oct. 24, 2000, both of which are incorporated byreference herein.

Referring to the general formula A_(a)M_(b)(XY₄)_(c)Z_(d), the amount(a′) of alkali metal that can be removed, as a function of the quantity(b′) and valency (V^(M)) of oxidizable metal, isa′=b′(ΔV ^(M)),where ΔV^(M) is the difference between the valence state of the metal inthe active material and a valence state readily available for the metal.(The term oxidation state and valence state are used in the artinterchangeably.) For example, for an active material comprising iron(Fe) in the +2 oxidation state, ΔV^(M)=1, wherein iron may be oxidizedto the +3 oxidation state (although iron may also be oxidized to a +4oxidation state in some circumstances). If b=2 (two moles of Fe per moleof material), the maximum amount (a′) of alkali metal (oxidation state+1) that can be removed during cycling of the battery is 2 (two moles ofalkali metal). If the active material comprises manganese (Mn) in the +2oxidation state, ΔV^(M)=2, wherein manganese may be oxidized to the +4oxidation state (although Mn may also be oxidized to higher oxidationstates in some circumstances). Thus, in this example, the maximum amount(a′) of alkali metal that can be removed during cycling of the batteryis 4, assuming that a≧4.

M may comprise a single metal, or a combination of two or more metals.In embodiments where M is a combination of elements, the total valenceof M in the active material must be such that the resulting activematerial is electrically neutral (i.e., the positive charges of allanionic species in the material balance the negative charges of allcationic species), as further discussed below. The net valence of M(V^(M)) having a mixture of elements (M1, M2 . . . Mt) may berepresented by the formulaV ^(M) =V ^(M1)b₁ +V ^(M2) b ₂ + . . . V ^(Mt) b _(t),where b₁+b₂+ . . . b_(t)=1, and V^(Mt) is the oxidation state of M1,V^(M2) is the oxidation state of M2, etc. (The net valence of M andother components of the electrode active material is discussed further,below.)

M may be, in general, a metal or metalloid, selected from the groupconsisting of elements from Groups 2-14 of the Periodic Table. Asreferred to herein, “Group” refers to the Group numbers (i.e., columns)of the Periodic Table as defined in the current IUPAC Periodic Table.See, e.g., U.S. Pat. No. 6,136,472, Barker et al., issued Oct. 24, 2000,incorporated by reference herein. In a preferred embodiment, M comprisesone or more transition metals from Groups 4 to 1. In another preferredembodiment, M comprises a mixture of metals, M′M″, where M′ is at leastone transition metal from Groups 4 to 1, and M″ is at least one elementwhich is from Groups 2, 3, 12, 13, or 14.

Transition metals useful herein include those selected from the groupconsisting of Ti (Titanium), V (Vanadium), Cr (Chromium), Mn(Manganese), Fe (Iron), Co (Cobalt), Ni (Nickel), Cu (Copper), Zr(Zirconium), Nb (Niobium), Mo (Molybdenum), Ru (Ruthenium), Rh(Rhodium), Pd (Palladium), Ag (Silver), Cd (Cadmium), Hf (Hafnium), Ta(Tantalum), W (Tungsten), Re (Rhenium), Os (Osmium), Ir (Iridium), Pt(Platinum), Au (Gold), Hg (Mercury), and mixtures thereof. Preferred arethe first row transition series (the 4th Period of the Periodic Table),selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, andmixtures thereof. Particularly preferred transition metals useful hereinclude Fe, Co, Mn, Cu, V, Cr, and mixtures thereof. In someembodiments, mixtures of transition metals are preferred. Although, avariety of oxidation states for such transition metals are available, insome embodiments it is preferred that the transition metals have a +2oxidation state.

M may also comprise non-transition metals and metalloids. Among suchelements are those selected from the group consisting of Group 2elements, particularly Be (Beryllium), Mg (Magnesium), Ca (Calcium), Sr(Strontium), Ba (Barium); Group 3 elements, particularly Sc (Scandium),Y (Yttrium), and the lanthanides, particularly La (Lanthanum), Ce(Cerium), Pr (Praseodymium), Nd (Neodymium), Sm (Samarium); Group 12elements, particularly Zn (zinc) and Cd (cadmium); Group 13 elements,particularly B (Boron), Al (Aluminum), Ga (Gallium), In (Indium), Tl(Thallium); Group 14 elements, particularly Si (Silicon), Ge(Germanium), Sn (Tin), and Pb (Lead); Group 15 elements, particularly As(Arsenic), Sb (Antimony), and Bi (Bismuth); Group 16 elements,particularly Te (Tellurium); and mixtures thereof. Preferrednon-transition metals include the Group 2 elements, Group 12 elements,Group 13 elements, and Group 14 elements. Particularly preferrednon-transition metals include those selected from the group consistingof Mg, Ca, Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof.Particularly preferred are non-transition metals selected from the groupconsisting of Mg, Ca, Zn, Ba, Al, and mixtures thereof.

As further discussed herein, “t” is selected so as to maintainelectroneutrality of the electrode active material. In a preferredembodiment, where c=1, b is from about 1 to about 2, preferably about 1.In another preferred embodiment, where c=2, b is from about 2 to about3, preferably about 2.

XY₄ is selected from the group consisting ofX′O_(4-x)Y′_(x)X′O_(4-y)Y′_(2y), X′S₄, and mixtures thereof, where X′ isP (phosphorus), As (arsenic), Sb (antimony), Si (silicon), Ge(germanium), S (sulfur), and mixtures thereof; X″ is P, As, Sb, Si, Geand mixtures thereof. In a preferred embodiment, X′ and X″ are,respectively, selected from the group consisting of P, Si, and mixturesthereof. In a particularly preferred embodiment, X′ and X″ are P. Y ishalogen, preferably F (fluorine).

In a preferred embodiment 0≦x<3; and 0<y<4, such that a portion of theoxygen (O) in the XY₄ moiety is substituted with halogen. In anotherpreferred embodiment, x and y are 0. In a particularly preferredembodiment XY₄ is X′O₄, where X′ is preferably P or Si, more preferablyP.

Z is OH, halogen, or mixtures thereof. In a preferred embodiment, Z isselected from the group consisting of OH (hydroxyl), F (fluorine), Cl(chlorine), Br (bromine) and mixtures thereof. In a preferredembodiment, Z is OH. In another preferred embodiment, Z is F, ormixtures of F with OH, Cl, or Br. Preferably “d” is from about 0.1 toabout 6, more preferably from about 0.2 to about 6. Where c=1, d ispreferably from about 0.1 to about 3, preferably from about 0.2 to about2. In a preferred embodiment, where c=1, d is about 1. Where c 2, d ispreferably from about 0.1 to about 6, preferably from about 1 to about6. Where c=3, d is preferably from about 0.1 to about 6, preferably fromabout 2 to about 6, preferably from about 3 to about 6.

The composition of M, X, Y, and Z, and the values of a, b, c, d, x andy, are selected so as to maintain electroneutrality of the electrodeactive material. As referred to herein “electroneutrality” is the stateof the electrode active material wherein the sum of the cationic chargedspecies (e.g., M and X) in the material is equal to the sum of theanionic charged species (e.g., Y and Z) in the material. Preferably, theXY₄ moieties are comprised to be, as a unit moiety, an anion having acharge of −2, −3, or −4, depending on the selection of X.

In general, the valence state of each component element of the electrodeactive material may be determined in reference to the composition andvalence state of the other component elements of the material. Byreference to the general formula A_(a)M_(b)(XY₄)_(c)Z_(d), theelectroneutrality of the material may be determined using the formula(V ^(A))a+(V ^(M))b+(V ^(X))c=(V ^(Y))4c+(V ^(Z))dwhere V^(A) is the net valence of A, V^(M) is the net valence of M,V^(Y) is the net valence of Y, and V^(Z) is the net valence of Z. Asreferred to herein, the “net valence” of a component is (a) the valencestate for a component having a single element which occurs in the activematerial in a single valence state; or (b) the mole-weighted sum of thevalence states of all elements in a component comprising more than oneelement, or comprising a single element having more than one valencestate. The net valence of each component is represented in the followingformulae.(V ^(A))b=[(V ^(A1))a ¹+(Val ^(A2))a ²+ . . . (Val ^(An))a ^(n) ]/n; a ¹+a ² + . . . a ^(n) =a(V ^(M))b=[(V ^(M1))b ¹+(V ^(M2))b ²+ . . . (V ^(Mn))b ^(n) ]/n; b ¹ +b² +b ^(n) =b(V ^(X))c=[(V ^(X1))c ¹+(V ^(X2))c ²+ . . . (V ^(X1))c ^(n) ]n ; c ¹ +c² + . . . c ^(n) =c(V ^(Y))c=[(V ^(Y1))c ¹+(V ^(Y2))c ²+ . . . (V ^(Yn))c ^(n) ]/n; C ¹ +c² + . . . c ^(n) =c(V ^(Z))c=[(V ^(Z1))c ¹+(V ^(Z2))c ²+ . . . (V ^(Zn))c ^(n) ]/n; c ¹ +c² + . . . c ^(n) =c

In general, the quantity and composition of M is selected given thevalency of X, the value of “c,” and the amount of A, so long as Mcomprises at least one metal that is capable of oxidation. Thecalculation for the valence of M can be simplified, where V^(A)=1,V^(Z)=1, as follows.For compounds where c=1: (V ^(M))b=(V ^(A))4+d−a−(V ^(X))For compounds where c=3: (V ^(M))b=(V ^(A))12+d−a−(V ^(X))3

The values of a, b, c, d, x, and y may result in stoichiometric ornon-stoichiometric formulas for the electrode active materials. In apreferred embodiment, the values of a, b, c, d, x, and y are all integervalues, resulting in a stoichiometric formula. In another preferredembodiment, one or more of a, b, c, d, x and y may have non-integervalues. It is understood, however, in embodiments having a latticestructure comprising multiple units of a non-stoichiometric formulaA_(a)M_(b)(XY₄)_(c)Z_(d), that the formula may be stoichiometric whenlooking at a multiple of the unit. That is, for a unit formula where oneor more of a, b, c, d, x, or y is a non-integer, the values of eachvariable become an integer value with respect to a number of units thatis the least common multiplier of each of a, b, c, d, x and y. Forexample, the active material Li₂Fe_(0.5)Mg_(0.5)PO₄F isnon-stoichiometric. However, in a material comprising two of such unitsin a lattice structure, the formula is Li₄FeMg(PO₄)₂F₂.

A preferred non-stoichiometric electrode active material is of theformula Li_(1+z)MPO₄F_(z) where 0<z≦3, preferably 0<z≦1. Anotherpreferred non-stoichiometric electrode active material is of the formulaLi^(1+z)M′_(1-y)M″_(y)PO₄F_(z); where 0<z<3, preferably 0<z<1; and0≦y<1. A particularly preferred non-stoichiometric active material isLi_(1.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25).

A preferred electrode active material embodiment comprises a compound ofthe formulaLi_(a)M_(b)(PO₄)Z_(d),

wherein

-   -   (a) 0.1<a≦4;    -   (b) M is M′M″, where M′ is at least one transition metal from        Groups 4 to 11 of the Periodic Table; and M″ is at least one        element which is from Group 2, 12, 13, or 14 of the Periodic        Table, and 1≦b≦3; and    -   (c) Z comprises halogen, and 0.1<d≦4; and    -   (d) wherein M, Z, a, b, and d are selected so as to maintain        electroneutrality of said compound.

Preferably, M′ is selected from the group consisting of Fe, Co, Ni, Mn,Cu, V, Zr, Ti, Cr, and mixtures thereof; more preferably M′ is selectedfrom the group consisting of Fe, Co, Mn, Cu, V, Cr, and mixturesthereof. Preferably, M″ is selected from the group consisting of Mg, Ca,Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof; more preferably M″is selected from the group consisting of Mg, Ca, Zn, Ba, Al, andmixtures thereof. Preferably Z comprises F.

Another preferred embodiment comprises a compound of the formulaLi_(a)m_(b)(PO₄)Z_(d),

wherein

-   -   (a) 0.1<a≦4;    -   (b) M is one or more metals, comprising at least one metal which        is capable of undergoing oxidation to a higher valence state,        and 1≦b≦3; and    -   (c) Z is OH or a mixture of OH and halogen, and 0.1<d≦4; and    -   (d) wherein M, Z, a, b, and d are selected so as to maintain        electroneutrality of said compound.

Preferably, M comprises M′M″, where M′ is at least one transition metalfrom Groups 4 to 11 of the Periodic Table; and M″ is at least oneelement from Groups 2, 3, 12, 13, or 14 of the Periodic Table.Preferably M′ is selected from the group consisting of Fe, Co, Ni, Mn,Cu, V, Zr, Ti, Cr, and mixtures thereof; more preferably M′ is selectedfrom the group consisting of Fe, Co, Mn, Cu, V, Cr, and mixturesthereof. Preferably M is not Ni, when a=2 and d=1. Preferably M″ isselected from the group consisting of Mg, Ca, Zn, Sr, Pb, Cd, Sn, Ba,Be, Al, and mixtures thereof; more preferably M″ is selected from thegroup consisting of Mg, Ca, Zn, Ba, Al, and mixtures thereof.

Another preferred embodiment comprises a compound of the formulaA₂M(PO₄)Z_(d),

wherein

-   -   (a) A is selected from the group consisting of Li, Na, K, and        mixtures thereof;    -   (b) M is M′_(1-b)M″b, where M′ is at least one transition metal        from Groups 4 to 11 of the Periodic Table; and M″ is at least        one element which is from Group 2, 3, 12, 13, or 14 of the        Periodic Table, and 0≦b<1; and    -   (c) Z comprises halogen, and 0.1<d≦2; and    -   (d) wherein M, Z, b, and d are selected so as to maintain        electroneutrality of said compound.

Preferably A is Li, or mixtures of Li with Na, K, or mixtures of Na andK. Preferably, M′ is selected from the group consisting of Fe, Co, Mn,Cu, V, Zr, Ti, Cr, and mixtures thereof; more preferably M′ is selectedfrom the group consisting of Fe, Co, Mn, Cu, V, Cr, and mixturesthereof. Preferably, M″ is selected from the group consisting of Mg, Ca,Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof; more preferably,M″ is selected from the group consisting of Mg, Ca, Zn, Ba, Al, andmixtures thereof. Preferably, Z comprises F. Preferably M is not Ni,when d=1. In a preferred embodiment M′ is Fe or Co, M″ is Mg, and X isF. A particularly preferred embodiment is Li₂Fe_(1-x)Mg_(x)PO₄F.Preferred electrode active materials include Li₂Fe_(0.9)Mg_(0.1)PO₄F,and Li₂Fe_(0.8)Mg_(0.2)PO₄F.

A preferred electrode active material is of the formula Li₂ MPO₄F,wherein M is selected from the group consisting of Ti, V, Cr, Mn, Fe,Co, Cu, Zn, or mixtures thereof, preferably Fe, Co, Mn, or mixturesthereof. Among such preferred compounds is Li₂CoPO₄F and Li₂FePO₄F.

Another preferred embodiment comprises a compound of the formula:A_(a)M_(b)(XY₄)₃Z_(d),

wherein

-   -   (a) A is selected from the group consisting of Li, Na, K, and        mixtures thereof, and 2≦a≦8;    -   (b) M comprises one or more metals, comprising at least one        metal which is capable of undergoing oxidation to a higher        valence state, and 1≦b≦3;    -   (c) XY₄ is selected from the group consisting of        X′O_(4-x)Y′_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof,        where X′ is P, As, Sb, Si, Ge, S, and mixtures thereof; X″ is P,        As, Sb, Si, Ge and mixtures thereof; Y′ is halogen; 0≦x<3; and        0<y<4;    -   (d) Z is OH, halogen, or mixtures thereof, and 0<d≦6; and    -   (e) wherein M, X, Y, Z, a, b, d, x and y are selected so as to        maintain electroneutrality of said compound.

In a preferred embodiment, A comprises Li, or mixtures of Li with Na orK. In another preferred embodiment, A comprises Na, K, or mixturesthereof. In a preferred embodiment, M comprises two or more transitionmetals from Groups 4 to 11 of the Periodic Table, preferably transitionmetals selected from the group consisting of Fe, Co, Ni, Mn, Cu, V, Zr,Ti, Cr, and mixtures thereof. In another preferred embodiment, Mcomprises M′M″, where M′ is at least one transition metal from Groups 4to 11 of the Periodic Table; and M″ is at least one element from Groups2, 3, 12, 13, or 14 of the Periodic Table having a +2 valence state.Preferably, M′ is selected from the group consisting of Fe, Co, Ni, Mn,Cu, V, Zr, Ti, Cr, and mixtures thereof; more preferably M′ is selectedfrom the group consisting of Fe, Co, Mn, Cu, V, Cr, and mixturesthereof. Preferably, M″ is selected from the group consisting of Mg, Ca,Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof; more preferably,M″ is selected from the group consisting of Mg, Ca, Zn, Ba, Al, andmixtures thereof. In a preferred embodiment, XY₄ is preferably PO₄. Inanother preferred embodiment, X′ comprises As, Sb, Si, Ge, S, andmixtures thereof; X″ comprises As, Sb, Si, Ge and mixtures thereof; and0<x<3. In a preferred embodiment, Z comprises F, or mixtures of F withCl, Br, OH, or mixtures thereof. In another preferred embodiment, Zcomprises OH, or mixtures thereof with Cl or Br. Preferred electrodeactives include those of the following formulae.

-   -   (a) A_(4+d)M′M″(PO₄)₃Z_(d) where M′ is a +3 oxidation state        transition or non-transition metal and M″ is a +2 oxidation        state transition metal or non-transition metal.    -   (b) A_(3+d)M′M″(PO₄)₃Z_(d) where M′ is a +4 oxidation state        transition metal or non-transition and M″ is a +2 oxidation        state transition metal or non-transition metal.    -   (c) A_(3+d)M₂(PO₄)₃Z_(d), where M is a +3 oxidation state        transition metal    -   (d) A_(1+d)M₂(PO₄)₃Z_(d), where M is a +4 oxidation state        transition metal    -   (e) A_(5+d)M₂(PO₄)₃Z_(d), where M is a +2 oxidation state        transition metal, or mixture with a +2 oxidation state        non-transition metal    -   (f) A_(2+d)M₂(SiO₄)₂(PO₄)Z_(d), where M is a +4 oxidation state        transition metal    -   (g) A_(3+2x+d)M₂(SiO₄)_(3-x)(PO₄)_(x)Z_(d), where M is a +3        oxidation state transition metal    -   (h) A_(4+d)M₂(SiO₄)₃Z_(d), where M is a +4 oxidation state        transition metal    -   (i) A_(6+d)M₂(SiO₄)₃Z_(d), where M is a +3 oxidation state        transition metal    -   (j) A_(2+d)M₂(SO₄)₃Z_(d), where M is a +2 oxidation state        transition metal, or mixture with a +2 oxidation state        non-transition metal    -   (k) A_(1+d)M′M″(SO₄)₃Z_(d), where M′ is a +2 oxidation state        metal; and M″ is a +3 oxidation state transition metal.

Among the preferred embodiments of this invention are the followingelectrode active materials: Li₂Fe_(0.8)Mg_(0.2)PO₄F;Li₂Fe_(0.5)Co_(0.5)PO₄F; Li₃CoPO₄F₂) KFe(PO₃F)F; Li₂Co(PO₃F)Br₂;Li₂Fe(PO₃F₂)F; Li₂FePO₄Cl; Li₂MnPO₄OH; Li₂CoPO₄F;Li₂Fe_(0.5)CO_(0.5)PO₄F; Li₂Fe_(0.9)Mg_(0.1)PO₄F;Li₂Fe_(0.8)Mg_(0.2)PO₄F; Li_(1.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25);Li₂MnPO₄F; Li₂CuPO₄F; K₂Fe_(0.9)Mg_(0.1)P_(0.5)As_(0.5)O₄F; Li₂MnSbO₄OH;Li₂Fe_(0.6)CO_(0.4)SbO₄Br; Na₃CoAsO₄F₂; LiFe(AsO₃F)Cl;Li₂Co(As_(0.5)Sb_(0.5)O₃F)F₂; K₂Fe(AsO₃F₂)F; Li₂NiSbO₄F; Li₂FeAsO₄OH;Li₃Mn₂(PO₄)₃F; Na₄FeMn(PO₄)₃OH; Li₄FeV(PO₄)₃Br; Li₃VAl(PO₄)₃F;K₃MgV(PO₄)₃Cl; LiKNaTiFe(PO₄)₃F; Li₄Fe₂(PO_(3.82)F_(0.68))₃;Li₃FeMn(PO_(3.67)F_(0.33))₃; Li₄Ti₂(PO₄)₃Br; Li₃V₂(PO₄)₃F₂;Li₆FeMg(PO₄)₃OH; Li₃Mn₂(AsO₄)₃F; K₄FeMn(AsO₄)₃OH;Li₄FeV(P_(0.5)Sb_(0.5)O₄)₃Br; LiNaKAlV(AsO₄)₃F; K₃MgV(SbO₄)₃Cl;Li₃TiFe(SbO₄)₃F; Li₄Fe₂(SbO_(3.82)F_(0.68))₃;Li₃FeMn(P_(0.5)AS_(0.5)O_(3.67)F_(0.33))₃; Li₄Ti₂(PO₄)₃F;Li_(3.25)V₂(PO₄)₃F_(0.25); Li₃Na_(0.75)Fe₂(PO₄)₃F_(0.75);Na_(4.5)Fe₂(PO₄)₃(OH)Cl_(0.5); K₈Ti₂(PO₄)₃F₃Br₂; K₈Ti₂(PO₄)₃F₅;Li₂Ti₂(PO₄)₃F; LiNa_(1.25)V₂(PO₄)₃F_(0.5)Cl_(0.75);K_(1.25)Mn₂(PO₄)₃OH_(0.25); LiNa_(1.25)KTiV(PO₄)₃(OH)_(1.25)Cl;Na₆Ti₂(PO₄)₃F₃Cl₂; Li₇Fe₂(PO₄)₃F₂; Li₈FeMg(PO₄)₃F_(2.25)Cl_(0.75);Li₅Na_(2.5)TiMn(PO₄)₃(OH)₂Cl_(0.5); Na₃K_(4.5)MnCa(PO₄)₃(OH)_(1.5)Br;K₉FeBa(PO₄)₃F₂Cl₂ Li₅Ti₂(SiO₄)₂(PO₄)F₂; Na₆Mn₂(SiO₄)₂(PO₄)F₂Cl;Li₅TiFe(PO₄)₃F; Na₄K₂VMg(PO₄)₃FCl; Li₄NaAlNi(PO₄)₃(OH);Li₃K₃FeMg(PO₄)₃F₂; Li₂Na₂K₂CrMn(PO₄)₃(OH)Br; Li₄TiCa(PO₄)₃F;Li₄Ti_(0.75)Fe_(1.5)(PO₄)₃F; Li₃NaSnFe(PO₄)₃(OH);Li₃NaGe_(0.5)Ni₂(PO₄)₃(OH); Na₃K₂VCo(PO₄)₃(OH)Cl; Li₃Na₂MnCa(PO₄)₃F(OH);Li₃NaKTiFe(PO₄)₃F; Li₆FeCo(SiO₄)₂(PO₄)F; Li₃Na₃TiV(SiO₄)₂(PO₄)F;K_(5.5)CrMn(SiO₄)₂(PO₄)Cl_(0.5); Li₃Na_(2.5)V₂(SiO₄)₂(PO₄)(OH)_(0.5);Na_(5.25)FeMn(SiO₄)₂(PO₄)Br_(0.25); Li₄NaVTi(SiO₄)₃F_(0.5)Cl_(0.5);Na₂K_(2.5)ZrV(SiO₄)₃F_(0.5); Li₄K₂MnV(SiO₄)3(OH)₂; Li₂Na₂KTi₂(SiO₄)₃F;K₆V₂(SiO₄)₃(OH)Br; Li₈FeMn(SiO₄)₃F₂; Na₃K_(4.5)CoNi(SiO₄)₃(OH)_(1.5);Li₃Na₂K₂TiV(SiO₄)₃(OH)_(0.5)Cl_(0.5); K₉VCr(SiO₄)₃F₂Cl;Li₄Na₄V₂(SiO₄)₃FBr; Li₄FeMg(SO₄)F₂; Na₂KNiCo(SO₄)(OH); Na₅MnCa(SO₄)F₂Cl;Li₃NaCuBa(SO₄)FBr; Li_(2.5)K_(0.5)FeZn(SO₄)F; Li₃MgFe(SO₄)₃F₂;Li₂NaCaV(SO₄)₃FCl; Na₄NiMn(SO₄)₃(OH)₂; NaKBaFe(SO₄)₃F;Li₂KCuV(SO₄)₃(OH)Br; Li_(1.5)CoPO₄F_(0.5); Li_(1.25)CuPO₄F_(0.25);Li_(1.75)FePO₄F_(0.75); Li_(1.66)MnPO₄F_(0.66);Li_(1.5)CO_(0.75)Ca_(0.25)PO₄F_(0.5);Li_(1.75)Co_(0.8)Mn_(0.2)PO₄F_(0.75);Li_(1.25)Fe_(0.75)Mg_(0.25)PO₄F_(0.25);Li_(1.66)Cu_(0.6)Zn_(0.4)PO₄F_(0.66);Li_(1.75)Mn_(0.8)Mg_(0.2)PO₄F_(0.75); Li₂CuSiF₆: LiCoSiO₄F; Li₂CoSiO₄F;KMnSiO₄Cl; KMn₂SiO₄Cl; Li₂VSiO₄(OH)₂; LiFeCuSiO₄F₂; LiFeSiO₃F₃;NaMnSiO₃F₄; Li₂CuSiO₃Cl₃; Li₂CuGeF; Li₂FeGeF; LiCoGeO₄F; Li₂CoGeO₄F;Li₃CoGeO₄F; NaMnSi_(0.5)Ge_(0.5)O₄Cl; Li₂TiGeO₄(OH)₂; LiFeCuGeO₄F₂;NaFeSi_(0.5)Ge_(0.5)O₃F₃; LiNaCuGeO₃Cl₃; Li₅Mn₂(SiO₄)₃FCl;Li₂K₂Mn₂(SiO₄)₃F; Na₃Mn(SiO_(3.66)F_(0.39))OH; Li₄CuFe(GeO₄)₃Cl;Li₃Mn₂(GeO₄)₃OH; Na₃K₂Mn₂(Si_(0.5)Ge_(0.5)O₄)₃F₂; Li₄Mn₂(GeO₄)₃F;KLi₂Fe₂(Si_(0.5)Ge_(0.5)O₄)Br; Li₄Fe(GeO_(3.66)F_(0.39))₃F;Na₃Mn(GeO_(3.66)F_(0.39))OH; LiMnSO₄F; NaFe_(0.9)Mg_(0.1)SO₄Cl;LiFeSO₄F; LiMnSO₄OH; KMnSO₄F; Li₄Mn₃(SO₄)₃OH; Li₅Fe₂Al(SO₄)₃Cl;Li₄Fe(SO_(1.32)F_(2.63))₃BrCl; Na₃Mn(SO_(1.32)F_(2.68))₃OH;Li₂FeAl(SO_(1.32)F_(2.68))₃F;

Li₂FeZn(PO₄)F₂: Li_(0.5)CO_(0.75)Mg_(0.5)(PO₄)F_(0.75);Li₃Mn_(0.5)Al_(0.5)(PO₄)F_(3.5); Li_(0.75)VCa(PO₄)F_(1.75);Li₄CuBa(PO₄)F₄; Li_(0.5)Mn_(0.5)Ca(PO₄)(OH)_(1.5);Li_(1.5)FeMg(PO₄)(OH)Cl; LiFeCoCa(PO₄)(OH)₃F; Li₃CuBa(PO₄)(OH)₂Br₂;Li_(0.75)Mn_(1.5)Al(PO₄)(OH)_(3.75); Li₂Co_(0.75)Mg_(0.25)(PO₄)F;LiNaCO_(0.8)Mg_(0.2)(PO₄)F; NaKCu_(0.5)Mg_(0.5)(PO₄)F;LiNa_(0.5)K_(0.5)Fe_(0.75)Mg_(0.25)(PO₄)F;Li_(1.5)K_(0.5)V_(0.5)Zn_(0.5)(PO₄)F₂; Li₆CuCa(SbO₂F₄)₃F;Na₆Fe₂Mg(PS₄)₃(OH₂)Cl; Li₄K₃CoAl(AsO₂F₄)₃F₃;Li₄Fe_(1.5)Co_(0.5)(PO₃F)₃(OH)_(3.5); K₈FeMg(PO₃F)₃F₃Cl₃Li₅Fe₂Al(SO₄)₃Cl; LiFe₂(SO₄)₃Cl, LiMn₂(SO₄)₃F, Li₃Ni₂(SO₄)₃Cl,Li₃CO₂(SO₄)₃F, Li₃Fe₂(SO₄)₃Br, Li₃Mn₂(SO₄)₃F, Li₃MnFe(SO₄)₃F,Li₃NiCo(SO₄)₃Cl; LiMnSO₄F; LiFeSO₄Cl; LiNiSO₄F; LiCoSO₄Cl;LiMn_(1-x)Fe_(x)SO₄F, LiFe_(1-x)Mg_(x)SO₄F; Li₇ZrMn(SiO₄)₃F,Li₇MnCo(SiO₄)₃F, Li₇MnNi(SiO₄)₃F, Li₇VAl(SiO₄)₃F; Li₄MnCo(PO₄)₂(SiO₄)F;Li₄VAl(PO₄)₂(SiO₄)F; Li₄MnV(PO₄)₂(SiO₄)F; Li₄CoFe(PO₄)₂(SiO₄)F;Li_(0.6)VPO₄F_(0.6); Li_(0.8)VPO₄F_(0.8); LiVPO₄F; Li₃V₂(PO₄)₂F₃;LiVPO₄Cl; LiVPO4OH; NaVPO₄F; Na₃V₂(PO₄)F; and mixtures thereof.

Methods of Manufacture:

Active materials of general formula A_(a)M_(b)(XY₄)_(c)Z_(d) are readilysynthesized by reacting starting materials in a solid state reaction,with or without simultaneous oxidation or reduction of the metal speciesinvolved. According to the desired values of a, b, c, and d in theproduct, starting materials are chosen that contain “a” moles of alkalimetal A from all sources, “b” moles of metals M from all sources, “c”moles of phosphate (or other XY₄ species) from all sources, and “d”moles of halide or hydroxide Z, again taking into account all sources.As discussed below, a particular starting material may the be source ofmore than one of the components A, M, XY₄, or Z. Alternatively it ispossible to run the reaction with an excess of one or more of thestarting materials. In such a case, the stoichiometry of the productwill be determined by the limiting reagent among the components A, M,XY₄, and Z. Because in such a case at least some of the startingmaterials will be present in the reaction product mixture, it is usuallydesirable to provide exact molar amounts of all the starting materials.

Sources of alkali metal include any of a number of salts or ioniccompounds of lithium, sodium, potassium, rubidium or cesium. Lithium,sodium, and potassium compounds are preferred. Preferably, the alkalimetal source is provided in powder or particulate form. A wide range ofsuch materials is well known in the field of inorganic chemistry.Non-limiting examples include the lithium, sodium, and/or potassiumfluorides, chlorides, bromides, iodides, nitrates, nitrites, sulfates,hydrogen sulfates, sulfites, bisulfites, carbonates, bicarbonates,borates, phosphates, hydrogen phosphates, dihydrogen phosphates,silicates, antimonates, arsenates, geiminates, oxides, acetates,oxalates, and the like. Hydrates of the above compounds may also beused, as well as mixtures. In particular, the mixtures may contain morethan one alkali metal so that a mixed alkali metal active material willbe produced in the reaction.

Sources of metals M include salts or compounds of any of the transitionmetals, alkaline earth metals, or lanthanide metals, as well as ofnon-transition metals such as aluminum, gallium, indium, thallium, tin,lead, and bismuth. The metal compounds include, without limitation,fluorides, chlorides, bromides, iodides, nitrates, nitrites, sulfates,hydrogen sulfates, sulfites, bisulfites, carbonates, bicarbonates,borates, phosphates, hydrogen phosphates, dihydrogen phosphates,silicates, antimonates, arsenates, germanates, oxides, hydroxides,acetates, oxalates, and the like. Hydrates may also be used, as well asmixtures of metals, as with the alkali metals, so that alkali metalmixed metal active materials are produced. The metal M in the startingmaterial may have any oxidation state, depending the oxidation staterequired in the desired product and the oxidizing or reducing conditionscontemplated, as discussed below. The metal sources are chosen so thatat least one metal in the final reaction product is capable of being inan oxidation state higher than it is in the reaction product.

Sources of the desired starting material anions such as the phosphates,halides, and hydroxides are provided by a number of salts or compoundscontaining positively charged cations in addition to the source ofphosphate (or other XY₄ species), halide, or hydroxide. Such cationsinclude, without limitation, metal ions such as the alkali metals,alkaline metals, transition metals, or other non-transition metals, aswell as complex cations such as ammonium or quaternary quaternaryammonium. The phosphate anion in such compounds may be phosphate,hydrogen phosphate, or dihydrogen phosphate. As with the alkali metalsource and metal source discussed above, the phosphate, halide, orhydroxide starting materials are preferably provided in particulate orpowder form. Hydrates of any of the above may be used, as can mixturesof the above.

A starting material may provide more than one of the components A, M,XY₄, and 2, as is evident in the list above. In various embodiments ofthe invention, starting materials are provided that combine, forexample, the alkali metal and halide together, or the metal and thephosphate. Thus for example, lithium, sodium, or potassium fluoride maybe reacted with a metal phosphate such as vanadium phosphate or chromiumphosphate, or with a mixture of metal compounds such as a metalphosphate and a metal hydroxide. In one embodiment, a starting materialis provided that contains alkali metal, metal, and phosphate. There iscomplete flexibility to select starting materials containing any of thecomponents of alkali metal A, metal M, phosphate (or other XY₄ moiety),and halide/hydroxide Z, depending on availability. Combinations ofstarting materials providing each of the components may also be used.

In general, any anion may be combined with the alkali metal cation toprovide the alkali metal source starting material, or with the metal Mcation to provide the metal M starting material. Likewise, any cationmay be combined with the halide or hydroxide anion to provide the sourceof Z component starting material, and any cation may be used ascounterion to the phosphate or similar XY₄ component. It is preferred,however, to select starting materials with counterions that give rise tovolatile by-products. Thus, it is desirable to choose ammonium salts,carbonates, oxides, hydroxides, and the like where possible. Startingmaterials with these counterions tend to form volatile by-products suchas water, ammonia, and carbon dioxide, which can be readily removed fromthe reaction mixture. This concept is well illustrated in the Examplesbelow.

The sources of components A, M, phosphate (or other XY₄ moiety), and Zmay be reacted together in the solid state while heating for a time andtemperature sufficient to make a reaction product. The startingmaterials are provided in powder or particulate form. The powders aremixed together with any of a variety of procedures, such as by ballmilling without attrition, blending in a mortar and pestle, and thelike. Thereafter the mixture of powdered starting materials iscompressed into a tablet and/or held together with a binder material toform a closely cohering reaction mixture. The reaction mixture is heatedin an oven, generally at a temperature of about 400° C. or greater untila reaction product forms. However, when Z in the active material ishydroxide, it is preferable to heat at a lower temperature so as toavoid volatilizing water instead of incorporating hydroxyl into thereaction product. Exemplary times and temperatures for the reaction aregiven in the Examples below.

When the starting materials contain hydroxyl for incorporation into thereaction product, the reaction temperature is preferably less than about400° C., and more preferably about 250° C. or less. One way of achievingsuch temperatures is to carry out the reaction hydrothermally, asillustrated in Examples 15 and 16. In a hydrothermal reaction, thestarting materials are mixed with a small amount of a liquid such aswater, and placed in a pressurized bomb. The reaction temperature islimited to that which can be achieved by heating the liquid water underpressure.

The reaction may be carried out without redox, or if desired underreducing or oxidizing conditions. When the reaction is done withoutredox, the oxidation state of the metal or mixed metals in the reactionproduct is the same as in the starting materials. Such a scheme isillustrated, for example, in Example 16. Oxidizing conditions may beprovided by running the reaction in air. Thus, oxygen from the air isused in Example 12 to oxidize the starting material cobalt having anaverage oxidation state of +2.67 (8/3) to an oxidation state of +3 inthe final product.

The reaction may also be carried out with reduction. For example, thereaction may be carried out in a reducing atmosphere such as hydrogen,ammonia, methane, or a mixture of reducing gases. Alternatively, thereduction may be carried out in situ by including the reaction mixture areductant that will participate in the reaction to reduce the metal M,but that will produce by-products that will not interfere with theactive material when used later in an electrode or an electrochemicalcell. One convenient reductant to use to make the active materials ofthe invention is a reducing carbon. In a preferred embodiment, thereaction is carried out in an inert atmosphere such as argon, nitrogen,or carbon dioxide. Such reducing carbon is conveniently provided byelemental carbon, or by an organic material that can decompose under thereaction conditions to form elemental carbon or a similar carboncontaining species that has reducing power. Such organic materialsinclude, without limitation, glycerol, starch, sugars, cokes, andorganic polymers which carbonize or pyrolize under the reactionconditions to produce a reducing form of carbon. A preferred source ofreducing carbon is elemental carbon. Carbothermal reduction isillustrated in Examples 7, 19, and 21.

The stoichiometry of the reduction can be selected along with therelative stoichiometric amounts of the starting components A, M, PO₄ (orother XY₄ moiety), and Z. It is usually easier to provide the reducingagent in stoichiometric excess and remove the excess, if desired, afterthe reaction. In the case of the reducing gases and the use of reducingcarbon such as elemental carbon, any excess reducing agent does notpresent a problem. In the former case, the gas is volatile and is easilyseparated from the reaction mixture, while in the latter, the excesscarbon in the reaction product does not harm the properties of theactive material, because carbon is generally added to the activematerial to form an electrode material for use in the electrochemicalcells and batteries of the invention. Conveniently also, the by-productscarbon monoxide or carbon dioxide (in the case of carbon) or water (inthe case of hydrogen) are readily removed from the reaction mixture.

A stoichiometry of reaction of a mixture of starting materials withhydrogen gas is illustrated in the table, giving the products formedwhen starting materials are reacted with ‘n’ moles of hydrogen accordingto the reaction:nH₂+Li₂CO₃+M₂O₅+LiF+3 NH₄H₂PO₄→Reaction Value of ‘n’ Reaction ProductVolatile by-products 1 Li₂M₂(PO₄)₃F 0.5 CO₂ + 3 NH₃ + 5.5 H₂O 1.5Li₃M₂(PO₄)₃F CO₂ + 3 NH₃ + 6 H₂O 2.5 Li₃M₂P₃O₁₁F CO₂ + 3 NH₃ + 7 H₂O

The extent of reduction is not dependent simply on the amount ofhydrogen present—it is always available in excess. It is dependent onthe temperature of reaction. Higher temperatures will facilitate greaterreducing power.

In addition whether one gets e.g. (PO₄)₃F or P₃O₁₁F in the final productdepend on the thermodynamics of formation of the product. The lowerenergy product will be favored.

At a temperature where only one mole of hydrogen reacts, the M⁺⁵ in thestarting material is reduced to M⁺⁴, allowing for the incorporation ofonly 2 lithiums in the reaction product. When 1.5 moles of hydrogenreact, the metal is reduced to M^(+3.5) on average, considering thestoichiometry of reduction. With 2.5 moles of hydrogen, the metal isreduced to M^(+2.5) on average. Here there is not enough lithium in thebalanced reaction to counterbalance along with the metal the −10 chargeof the (PO₄)₃F group. For this reason, the reaction product has insteada modified P₃O₁₁F moiety with a charge of −8, allowing the Li₃ tobalance the charge. The table illustrates how important it is toconsider all the stoichiometries when synthesizing the A₃M_(b)(PO₄)_(c)Z_(d) active materials of the invention.

When using a reducing atmosphere, it is difficult to provide less thanan excess of reducing gas such as hydrogen. Under such as a situation,it is preferred to control the stoichiometry of the reaction by theother limiting reagents, as illustrated in the table. Alternatively thereduction may be carried out in the presence of reducing carbon such aselemental carbon. Experimentally, it would be possible to use preciseamounts of reductant carbon as illustrated in the table for the case ofreductant hydrogen to make products of a chosen stoichiometry. However,it is preferred to carry out the carbothermal reduction in a molarexcess of carbon. As with the reducing atmosphere, this is easier to doexperimentally, and it leads to a product with excess carbon dispersedinto the reaction product, which as noted above provides a useful activeelectrode material.

The carbothermal reduction method of synthesis of mixed metal phosphateshas been described in PCT Publication WO/01/53198, Barker et al.,incorporated by reference herein. The carbothermal method may be used toreact starting materials in the presence of reducing carbon to form avariety of products. The carbon functions to reduce a metal ion in thestarting material metal M source. The reducing carbon, for example inthe form of elemental carbon powder, is mixed with the other startingmaterials and heated. For best results, the temperature should be about400° C. or greater, and up to about 950° C. Higher temperatures may beused, but are usually not required.

Generally, higher temperature (about 650° C. to about 1000° C.)reactions produce CO as a by-product whereas CO₂ production is favoredat lower temperatures (generally up to about 650° C.). The highertemperature reactions produce CO effluent and the stoichiometry requiresmore carbon be used than the case where CO₂ effluent is produced atlower temperature. This is because the reducing effect of the C to CO)reaction is greater than the C to CO reaction. The C to CO₂ reactioninvolves an increase in carbon oxidation state of +4 (from 0 to 4) andthe C to CO reaction involves an increase in carbon oxidation state of+2 (from ground state zero to 2). In principle, such would affect theplanning of the reaction, as one would have to consider not only thestoichiometry of the reductant but also the temperature of the reaction.When an excess of carbon is used, however, such concerns do not arise.It is therefore preferred to use an excess of carbon, and control thestoichiometry of the reaction with another of the starting materials aslimiting reagent.

As noted above, the active materials A_(a)M_(b)(XY₄)_(c)Z_(d) of theinvention can contain a mixture of alkali metals A, a mixture of metalsB, a mixture of components Z, and a phosphate group representative ofthe XY₄ group in the formula. In another aspect of the invention, thephosphate group can be completely or partially substituted by a numberof other XY₄ moieties, which will also be referred to as “phosphatereplacements” or “modified phosphates”. Thus, active materials areprovided according to the invention wherein the XY₄ moiety is aphosphate group that is completely or partially replaced by suchmoieties as sulfate (SO₄ ²⁻), monofluoromonophosphate, (PO₃F²⁻),difluoromonophosphate (PO²F²⁻), silicate (SiO₄ ⁴⁻), arsenate,antimonate, and germanate. Analogues of the above oxygenate anions wheresome or all of the oxygen is replaced by sulfur are also useful in theactive materials of the invention, with the exception that the sulfategroup may not be completely substituted with sulfur. For examplethiomonophosphates may also be used as a complete or partial replacementfor phosphate in the active materials of the invention. Suchthiomonophosphates include the anions PO₃S³⁻, PO₂S₂ ³⁻, POS₃ ³⁻, and PS₄³⁻. They are most conveniently available as the sodium, lithium, orpotassium derivative.

To synthesize the active materials containing the modified phosphatemoieties, it is usually possible to substitute all or part of thephosphate compounds discussed above with a source of the replacementanion. The replacement is considered on a stoichiometric basis and thestarting materials providing the source of the replacement anions areprovided along with the other starting materials as discussed above.Synthesis of the active materials containing the modified phosphategroups proceeds as discussed above, either without redox or underoxidizing or reducing conditions. As was the case with the phosphatecompounds, the compound containing the modified or replacement phosphategroup or groups may also be a source of other components of the activematerials. For example, the alkali metal and/or the mixed metal M may bea part of the modified phosphate compound.

Non-limiting examples of sources of monofluoromonophosphates includeNa₂PO₃F, K₂PO₃F, (NH₄)₂PO₃F.H₂O, LiNaPO₃F.H₂O, LiKPO₃F, LiNH4PO₃F,NaNH₄PO₃F, NaK₃(PO₃F)₂ and CaPO₃F-2H₂O. Representative examples ofsources of difluoromonophosphate compounds include, without limitation,NH4PO₂F₂, NaPO₂F₂, KPO₂F₂, Al(PO₂F₂)₃, and Fe(PO₂F₂)₃.

When it is desired to partially or completely substitute phosphorous inthe active materials for silicon, it is possible to use a wide varietyof silicates and other silicon containing compounds. Thus, usefulsources of silicon in the active materials of the invention includeorthosilicates, pyrosilicates, cyclic silicate anions such as Si₃O₉ ⁶,Si₆O₁₈ ¹²⁻ and the like and pyrocenes represented by the formula (SiO₃²⁻)_(n) for example LiAl(SiO₃)₂. Silica or SiO₂ may also be used.Partial substitution of silicate for phosphate is illustrated in Example23.

Representative arsenate compounds that may be used to prepare the activematerials of the invention include H₃AsO₄ and salts of the anions[H₂AsO₄]²⁻ and HAsO₄]²⁻. Sources of antimonate in the active materialscan be provided by antimony-containing materials such as Sb₂O₅,M^(I)SbO₃ where M^(I) is a metal having oxidation state +1, M^(III)SbO₄where M^(III) is a metal having an oxidation state of +3, andM^(II)Sb₂O₇ where M″ is a metal having an oxidation state of +2.Additional sources of antimonate include compounds such as Li₃SbO₄,NH₄H₂SbO₄, and other alkali metal and/or ammonium mixed salts of the[SbO₄]³⁻ anion. Partial substitution of phosphate by antimonate isillustrated in Example 24.

Sources of sulfate compounds that can be used to partially or completelyreplace phosphorous in the active materials with sulfur include alkalimetal and transition metal sulfates and bisulfates as well as mixedmetal sulfates such as (NH₄)₂Fe(SO₄)₂, NH₄Fe(SO₄)₂ and the like.Finally, when it is desired to replace part or all of the phosphorous inthe active materials with germanium, a germanium containing compoundsuch as GeO₂ may be used.

To prepare the active materials containing the modified phosphategroups, it suffices to choose the stoichiometry of the startingmaterials based on the desired stoichiometry of the modified phosphategroups in the final product and react the starting materials togetheraccording to the procedures described above with respect to thephosphate materials. Naturally, partial or complete substitution of thephosphate group with any of the above modified or replacement phosphategroups will entail a recalculation of the stoichiometry of the requiredstarting materials.

In a preferred embodiment, a two-step method is used to prepare thegeneral formula Li_(1+x)MPO₄F_(x) which consists of the initialpreparation of a LiMPO₄ compound (step 1), which is then reacted with xmoles of LiF to provide Li₂ MPO₄F (step 2). The starting (precursor)materials for the first step include a lithium containing compound, ametal containing compound and a phosphate containing compound. Each ofthese compounds may be individually available or may be incorporatedwithin the same compounds, such as a lithium metal compound or a metalphosphate compound.

Following the preparation in step one, step two of the reaction proceedsto react the lithium metal phosphate (provided in step 1) with a lithiumsalt, preferably lithium fluoride (LiF). The LiF is mixed in proportionwith the lithium metal phosphate to provide a lithiated transition metalfluorophosphate product. The lithiated transition metal fluorophosphatehas the capacity to provide lithium ions for electrochemical potential.

In addition to the previously described two-step method, a one stepreaction method may be used in preparing such preferred materials of thepresent invention. In one method of this invention, the startingmaterials are intimately mixed and then reacted together when initiatedby heat. In general, the mixed powders are pressed into a pellet. Thepellet is then heated to an elevated temperature. This reaction can berun under an air atmosphere or a non-oxidizing atmosphere. In anothermethod, the lithium metal phosphate compound used as a precursor for thelithiated transition metal fluorophosphate reaction can be formed eitherby a carbothermal reaction, or by a hydrogen reduction reaction.

The general aspects of the above synthesis route are applicable to avariety of starting materials. The metal compounds may be reduced in thepresence of a reducing agent, such as hydrogen or carbon. The sameconsiderations apply to other metal and phosphate containing startingmaterials. The thermodynamic considerations such as ease of reduction ofthe selected starting materials, the reaction kinetics, and the meltingpoint of the salts will cause adjustment in the general procedure, suchas the amount of reducing agent, the temperature of the reaction, andthe dwell time.

The first step of a preferred two-step method includes reacting alithium containing compound (lithium carbonate, Li₂CO₃), a metalcontaining compound having a phosphate group (for example, nickelphosphate, Ni₃(PO₄)₂.xH₂O, which usually has more than one mole ofwater), and a phosphoric acid derivative (such as a diammonium hydrogenphosphate, DAHP). The powders are pre-mixed with a mortar and pestleuntil uniformly dispersed, although various methods of mixing may beused. The mixed powders of the starting materials are pressed intopellets. The first stage reaction is conducted by heating the pellets inan oven at a preferred heating rate to an elevated temperature, and heldat such elevated temperature for several hours. A preferred ramp rate ofabout 2° C./minute is used to heat to a preferable temperature of about800° C. Although in many instances a heating rate is desirable for areaction, it is not always necessary for the success of the reaction.The reaction is carried out under a flowing air atmosphere (e.g., when Mis Ni or Co), although the reaction could be carried out in an inertatmosphere such as N₂ or Ar (when M is Fe). The flow rate will depend onthe size of the oven and the quantity needed to maintain the atmosphere.The reaction mixture is held at the elevated temperature for a timesufficient for the reaction product to be formed. The pellets are thenallowed to cool to ambient temperature. The rate at which a sample iscooled may vary.

In the second step, the Li₂MPO₄F active material is prepared by reactingthe LiMPO₄ precursor made in step one with a lithium salt, preferablylithium fluoride LiF. Alternatively, the precursors may include alithium salt other than a halide (for example, lithium carbonate) and ahalide material other than lithium fluoride (for example ammoniumfluoride). The precursors for step 2 are initially pre-mixed using amortar and pestle until uniformly dispersed. The mixture is thenpelletized, for example by using a manual pellet press and anapproximate 1.5″ diameter die-set. The resulting pellet is preferablyabout 5 mm thick and uniform. The pellets are then transferred to atemperature-controlled tube furnace and heated at a preferred ramp rateof about 2° C./minute to an ultimate temperature of about 800° C. Theentire reaction is conducted in a flowing argon gas atmosphere. Prior tobeing removed from the box oven, the pellet is allowed to cool to roomtemperature. As stated previously, the rate in which the pellet iscooled does not seem to have a direct impact on the product.

Examples 1-6, and 8 illustrate the two step process described above,while Examples 7, 11, 12, and 13 show a one-step procedure. Example 9gives a two-step procedure for making sodium-containing active materialsof the invention.

An alternate embodiment of the present invention is the preparation of amixed metal-lithium fluorophosphate compound. Example 6 demonstrates thetwo stage reaction resulting in the general nominal formula Li₂M′_(x)M″_(1-x)PO₄F wherein 0≦x<1. In general, a lithium or other alkali metalcompound, at least two metal compounds, and a phosphate compound arereacted together in a first step to provide a lithium mixed metalphosphate precursor. As previously described in other reactions, thepowders are mixed together and pelletized. The pellet is thentransferred to a temperature-controlled tube furnace equipped with aflowing inert gas (such as argon). The sample is then heated for exampleat a ramp rate of about 2° C./minute to an ultimate temperature of about750° C. and maintained at this temperature for eight hours or until areaction product is formed. As can be seen in various examples, thespecific temperatures used vary depending on what initial compounds wereused to form the precursor, but the standards described in no way limitthe application of the present invention to various compounds. Inparticular, a high temperature is desirable due to the carbothermalreaction occurring during the formation of the precursor. Following theheating of the pellet for a specified period of time, the pellet wascooled to room temperature.

The second stage provides the reaction of the lithium mixed metalphosphate compound with an alkali metal halide such as lithium fluoride.Following the making of the pellet from the lithium mixed metalphosphate precursor and the lithium fluoride, the pellet is placedinside a covered and sealed nickel crucible and transferred to a boxoven. In general, the nickel crucible is a convenient enclosure for thepellet although other suitable containers, such as a ceramic crucible,may also be used. The sample is then heated rapidly to an ultimatetemperature of about 700° C. and maintained at this temperature forabout 15 minutes. The crucible is then removed from the box oven andcooled to room temperature. The result is a lithiated transition metalfluorophosphate compound of the present invention.

In addition to the general nominal formula Li₂M′_(x)M″_(1-x)PO₄F, anon-stoichiometric mixed metal lithium fluorophosphate having thegeneral nominal formula Li_(1+z)M′_(y)M″_(1-y)PO₄F_(z) is provided inExample 8. The same conditions are met when preparing thenon-stoichiometric formula as are followed when preparing thestoichiometric formula, such as Example 6. In Example 8, the mole ratioof lithiated transition metal phosphate precursor to lithium fluoride isabout 1.0 to 0.25. The precursor compounds are pre-mixed using a mortarand pestle and then pelletized. The pellet is then placed inside acovered and sealed crucible and transferred to a box oven. The sample israpidly heated to an ultimate temperature of about 700° C. andmaintained at this temperature for about 15 minutes. Similar conditionsapply when preparing the nominal general formula Li_(1-z)MPO₄F_(z).

Referring back to the discussion of the lithium fluoride and metalphosphate reaction, the temperature of reaction is preferably about 400°C. or higher but below the melting point of the metal phosphate, andmore preferably at about 700° C. It is preferred to heat the precursorsat a ramp rate in a range from a fraction of a degree to about 10° C.per minute and preferably about 2° C. per minute. Once the desiredtemperature is attained, the reactions are held at the reactiontemperature from about 10 minutes to several hours, depending on thereaction temperature chosen. The heating may be conducted under an airatmosphere, or if desired may be conducted under a non-oxidizing orinert atmosphere. After reaction, the products are cooled from theelevated temperature to ambient (room) temperature (i.e. from about 10°C. to about 40° C.). Desirably, the cooling occurs at a rate of about50° C./minute. Such cooling has been found to be adequate to achieve thedesired structure of the final product in some cases. It is alsopossible to quench the products at a cooling rate on the order of about100° C./minute. In some instances, such rapid cooling may be preferred.A generalized rate of cooling has not been found applicable for certaincases, therefore the suggested cooling requirements vary.

Electrodes:

The present invention also provides electrodes comprising an electrodeactive material of the present invention. In a preferred embodiment, theelectrodes of the present invention comprise an electrode activematerial of this invention, a binder; and an electrically conductivecarbonaceous material.

In a preferred embodiment, the electrodes of this invention comprise:

-   -   (a) from about 25% to about 95%, more preferably from about 50%        to about 90%, active material;    -   (b) from about 2% to about 95% electrically conductive material        (e.g., carbon black); and    -   (c) from about 3% to about 20% binder chosen to hold all        particulate materials in contact with one another without        degrading ionic conductivity.

(Unless stated otherwise, all percentages herein are by weight.)Cathodes of this invention preferably comprise from about 50% to about90% of active material, about 5% to about 30% of the electricallyconductive material, and the balance comprising binder. Anodes of thisinvention preferably comprise from about 50% to about 95% by weight ofthe electrically conductive material (e.g., a preferred graphite), withthe balance comprising binder.

Electrically conductive materials among those useful herein includecarbon black, graphite, powdered nickel, metal particles, conductivepolymers (e.g., characterized by a conjugated network of double bondslike polypyrrole and polyacetylene), and mixtures thereof. Bindersuseful herein preferably comprise a polymeric material and extractableplasticizer suitable for forming a bound porous composite. Preferredbinders include halogenated hydrocarbon polymers (such aspoly(vinylidene chloride) and poly((dichloro-1,4-phenylene)ethylene),fluorinated urethanes, fluorinated epoxides, fluorinated acrylics,copolymers of halogenated hydrocarbon polymers, epoxides, ethylenepropylene diamine termonomer (EPDM), ethylene propylene diaminetermonomer (EPDM), polyvinylidene difluoride (PVDF), hexafluoropropylene(HFP), ethylene acrylic acid copolymer (EAA), ethylene vinyl acetatecopolymer (EVA), EAA/EVA copolymers, PVDFI/HFP copolymers, and mixturesthereof.

In a preferred process for making an electrode, the electrode activematerial is mixed into a slurry with a polymeric binder compound, asolvent, a plasticizer, and optionally the electroconductive material.The active material slurry is appropriately agitated, and then thinlyapplied to a substrate via a doctor blade. The substrate can be aremovable substrate or a functional substrate, such as a currentcollector (for example, a metallic grid or mesh layer) attached to oneside of the electrode film. In one embodiment, heat or radiation isapplied to evaporate the solvent from the electrode film, leaving asolid residue. The electrode film is further consolidated, where heatand pressure are applied to the film to sinter and calendar it. Inanother embodiment, the film may be air-dried at moderate temperature toyield self-supporting films of copolymer composition. If the substrateis of a removable type it is removed from the electrode film, andfurther laminated to a current collector. With either type of substrateit may be necessary to extract the remaining plasticizer prior toincorporation into the battery cell.

Batteries:

The batteries of the present invention comprise:

(a) a first electrode comprising an active material of the presentinvention;

(b) a second electrode which is a counter-electrode to said firstelectrode; and

(c) an electrolyte between said electrodes.

The electrode active material of this invention may comprise the anode,the cathode, or both. Preferably, the electrode active materialcomprises the cathode.

The active material of the second, counter-electrode is any materialcompatible with the electrode active material of this invention. Inembodiments where the electrode active material comprises the cathode,the anode may comprise any of a variety of compatible anodic materialswell known in the art, including lithium, lithium alloys, such as alloysof lithium with aluminum, mercury, manganese, iron, zinc, andintercalation based anodes such as those employing carbon, tungstenoxides, and mixtures thereof. In a preferred embodiment, the anodecomprises:

-   -   (a) from about 0% to about 95%, preferably from about 25% to        about 95%, more preferably from about 50% to about 90%, of an        insertion material;    -   (b) from about 2% to about 95% electrically conductive material        (e.g., carbon black); and    -   (c) from about 3% to about 20% binder chosen to hold all        particulate materials in contact with one another without        degrading ionic conductivity.

In a particularly preferred embodiment, the anode comprises from about50% to about 90% of an insertion material selected from the group activematerial from the group consisting of metal oxides (particularlytransition metal oxides), metal chalcogenides, and mixtures thereof. Inanother preferred embodiment, the anode does not contain an insertionactive, but the electrically conductive material comprises an insertionmatrix comprising carbon, graphite, cokes, mesocarbons and mixturesthereof. One preferred anode intercalation material is carbon, such ascoke or graphite, which is capable of forming the compound Li_(x)C.Insertion anodes among those useful herein are described in U.S. Pat.No. 5,700,298, Shi et al., issued Dec. 23, 1997; U.S. Pat. No.5,712,059, Barker et al., issued Jan. 27, 1998; U.S. Pat. No. 5,830,602,Barker et al., issued Nov. 3, 1998; and U.S. Pat. No. 6,103,419, Saidiet al., issued Aug. 15, 2000; all of which are incorporated by referenceherein.

In embodiments where the electrode active material comprises the anode,the cathode preferably comprises.

-   -   (a) from about 25% to about 95%, more preferably from about 50%        to about 90%, active material;    -   (b) from about 2% to about 95% electrically conductive material        (e.g., carbon black); and    -   (c) from about 3% to about 20% binder chosen to hold all        particulate materials in contact with one another without        degrading ionic conductivity.

Active materials useful in such cathodes include electrode activematerials of this invention, as well as metal oxides (particularlytransition metal oxides), metal chalcogenides, and mixtures thereof.Other active materials include lithiated transition metal oxides such asLiCoO₂, LiNiO₂, and mixed transition metal oxides such asLiCo_(x)Ni_(1-x)O₂, where 0<x<1. Another preferred active materialincludes lithiated spinet active materials exemplified by compositionshaving a structure of LiMn₂O₄, as well as surface treated spinels suchas disclosed in U.S. Pat. No. 6,183,718, Barker et at., issued Feb. 6,2001, incorporated by reference herein. Blends of two or more of any ofthe above active materials may also be used. The cathode mayalternatively further comprise a basic compound to protect againstelectrode degradation as described in U.S. Pat. No. 5,869,207, issuedFeb. 9, 1999, incorporated by reference herein.

The batteries of this invention also comprise a suitable electrolytethat provides for transfer of ions between the cathode and anode. Theelectrolyte is preferably a material that exhibits high ionicconductivity, as well as having insular properties to preventself-discharging during storage. The electrolyte can be either a liquidor a solid. Solid electrolytes preferably comprise a polymeric matrixwhich contains an ionic conductive medium. A liquid electrolytepreferably comprises a solvent and an alkali metal salt that form anionically conducting liquid.

One preferred embodiment is a solid polymeric electrolyte, comprising asolid polymeric matrix of an electrolyte compatible material formed bypolymerizing an organic or inorganic monomer (or partial polymerthereof) and which, when used in combination with the other componentsof the electrolyte, results in a solid state electrolyte. Suitable solidpolymeric matrices include those well known in the art and include solidmatrices formed from organic polymers, inorganic polymers or a solidmatrix forming monomer and from partial polymers of a solid matrixforming monomer.

The polymeric electrolyte matrix comprises a salt, typically inorganic,which is homogeneously dispersed via a solvent vehicle throughout thematrix. The solvent is preferably a low molecular weight organic solventadded to the electrolyte, which may serve the purpose of solvating theinorganic ion salt. The solvent is preferably any compatible, relativelynon-volatile, aprotic, relatively polar solvent, including dimethylcarbonaten (DMC), diethyl carbonate (DEC), dipropylcarbonate (DPC),ethyl methyl carbonate (EMC), butylene carbonate, gamma-butyrolactone,triglyme, tetraglyme, lactones, esters, dimethylsulfoxide, dioxolane,sulfolane, and mixtures thereof. Preferred solvents include ECIDMC,EC/DEC, EC/DPC and EC/EMC. Preferably, the inorganic ion salt is alithium or sodium salt, such as for example, LiAsF₆, LiPF₆, LiClO₄,LiB(C₆H₅)₄, LiAlCl₄, LiBr, and mixtures thereof, with the less toxicsalts being preferable. The salt content is preferably from about 5% toabout 65%, preferably from about 8% to about 35%. A preferred embodimentis a mixture of EC:DMC:LiPF₆ in a weight ratio of about 60:30:10.Electrolyte compositions among those useful herein are described in U.S.Pat. No. 5,418,091, Gozdz et al., issued May 23, 1995; U.S. Pat. No.5,508,130, Golovin, issued Apr. 16, 1996; U.S. Pat. No. 5,541,020,Golovin et al., issued Jul. 30, 1996; U.S. Pat. No. 5,620,810, Golovinet al., issued Apr. 15, 1997; U.S. Pat. No. 5,643,695, Barker et al.,issued Jul. 1, 1997; U.S. Pat. No. 5,712,059, Barker et al., issued Jan.27, 1997; U.S. Pat. No. 5,851,504, Barker et al., issued Dec. 22, 1998;U.S. Pat. No. 6,020,087, Gao, issued Feb. 1, 2001; and U.S. Pat. No.6,103,419, Saidi et al., issued Aug. 15, 2000; all of which areincorporated by reference herein.

Additionally, the electrolyte comprises a separator, or is surrounded bya separator membrane. The separator allows the migration of ions throughthe membrane while still providing a physical separation of the electriccharge between the electrodes, to prevent short-circuiting. Preferably,the separator also inhibits elevated temperatures within the batterythat can occur due to uncontrolled reactions, preferably by degradingupon high temperatures to provide infinite resistance to prevent furtheruncontrolled reactions. In a preferred embodiment, the polymeric matrixof the electrolyte can contain an additional polymer (a separator) orthe original polymeric matrix itself may function as a separator,providing the physical isolation needed between the anode and cathode.

A preferred electrolyte separator film comprises approximately two partspolymer for every one part of a preferred fumed silica. The conductivesolvent comprises any number of suitable solvents and salts. Desirablesolvents and salts are described in U.S. Pat. No. 5,643,695, Barker etal., issued Jul. 1, 1997; and U.S. Pat. No. 5,418,091, Gozdz et al.,issued May 23, 1995; both of which are incorporated by reference herein.One example is a mixture of EC:DMC:LiPF₆ in a weight ratio of about60:30:10.

A separator membrane element is generally polymeric and prepared from acomposition comprising a copolymer. A preferred composition is the 75 to92% vinylidene fluoride with 8 to 25% hexafluoropropylene copolymer(available commercially from Atochem North America as Kynar FLEX) and anorganic solvent plasticizer. Such a copolymer composition is alsopreferred for the preparation of the electrode membrane elements, sincesubsequent laminate interface compatibility is ensured. The plasticizingsolvent may be one of the various organic compounds commonly used assolvents for electrolyte salts, e.g., propylene carbonate or ethylenecarbonate, as well as mixtures of these compounds. Higher-boilingplasticizer compounds such as dibutyl phthalate, dimethyl phthalate,diethyl phthalate, and tris butoxyethyl phosphate are preferred.Inorganic filler adjuncts, such as fumed alumina or silanized fumedsilica, may be used to enhance the physical strength and melt viscosityof a separator membrane and, in some compositions, to increase thesubsequent level of electrolyte solution absorption.

A preferred battery comprises a laminated cell structure, comprising ananode layer, a cathode layer, and electrolyte/separator between theanode and cathode layers. The anode and cathode layers comprise acurrent collector. A preferred current collector is a copper collectorfoil, preferably in the form of an open mesh grid. The current collectoris connected to an external current collector tab, for a description oftabs and collectors. Such structures are disclosed in, for example, U.S.Pat. No. 4,925,752, Fauteux et al, issued May 15, 1990; U.S. Pat. No.5,011,501, Shackle et al., issued Apr. 30, 1991; and U.S. Pat. No.5,326,653, Chang, issued Jul. 5, 1994; all of which are incorporated byreference herein. In a battery embodiment comprising multipleelectrochemical cells, the anode tabs are preferably welded together andconnected to a nickel lead. The cathode tabs are similarly welded andconnected to a welded lead, whereby each lead forms the polarized accesspoints for the external load.

Lamination of assembled cell structures is accomplished by conventionalmeans by pressing between metal plates at a temperature of about120-160° C. Subsequent to lamination, the battery cell material may bestored either with the retained plasticizer or as a dry sheet afterextraction of the plasticizer with a selective low-boiling pointsolvent. The plasticizer extraction solvent is not critical, andmethanol or ether are often used.

In a preferred embodiment, a electrode membrane comprising the electrodeactive material (e.g., an insertion material such as carbon or graphiteor a insertion compound) dispersed in a polymeric binder matrix. Theelectrolyte/separator film membrane is preferably a plasticizedcopolymer, comprising a polymeric separator and a suitable electrolytefor ion transport. The electrolyte/separator is positioned upon theelectrode element and is covered with a positive electrode membranecomprising a composition of a finely divided lithium insertion compoundin a polymeric binder matrix. An aluminum collector foil or gridcompletes the assembly. A protective bagging material covers the celland prevents infiltration of air and moisture.

In another embodiment, a multi-cell battery configuration may beprepared with copper current collector, a negative electrode, anelectrolyte/separator, a positive electrode, and an aluminum currentcollector. Tabs of the current collector elements form respectiveterminals for the battery structure.

In a preferred embodiment of a lithium-ion battery, a current collectorlayer of aluminum foil or grid is overlaid with a positive electrodefilm, or membrane, separately prepared as a coated layer of a dispersionof insertion electrode composition. This is preferably an insertioncompound such as the active material of the present invention in powderform in a copolymer matrix solution, which is dried to form the positiveelectrode. An electrolyte/separator membrane is formed as a driedcoating of a composition comprising a solution containing VdF:HFPcopolymer and a plasticizer solvent is then overlaid on the positiveelectrode film. A negative electrode membrane formed as a dried coatingof a powdered carbon or other negative electrode material dispersion ina VdF:HFP copolymer matrix solution is similarly overlaid on theseparator membrane layer. A copper current collector foil or grid islaid upon the negative electrode layer to complete the cell assembly.Therefore, the VdF:HFP copolymer composition is used as a binder in allof the major cell components, positive electrode film, negativeelectrode film, and electrolyte/separator membrane. The assembledcomponents are then heated under pressure to achieve heat-fusion bondingbetween the plasticized copolymer matrix electrode and electrolytecomponents, and to the collector grids, to thereby form an effectivelaminate of cell elements. This produces an essentially unitary andflexible battery cell structure.

Cells comprising electrodes, electrolytes and other materials amongthose useful herein are described in the following documents, all ofwhich are incorporated by reference herein: U.S. Pat. No. 4,668,595,Yoshino et al., issued May 26, 1987; U.S. Pat. No. 4,792,504, Schwab etal., issued Dec. 20, 1988; U.S. Pat. No. 4,830,939, Lee et al., issuedMay 16, 1989; U.S. Pat. No. 4,935,317, Fauteaux et al., issued Jun. 19,1980; U.S. Pat. No. 4,990,413, Lee et al., issued Feb. 5, 1991; U.S.Pat. No. 5,037,712, Shackle et al., issued Aug. 6, 1991; U.S. Pat. No.5,262,253, Golovin, issued Nov. 16, 1993; U.S. Pat. No. 5,300,373,Shackle, issued Apr. 5, 1994; U.S. Pat. No. 5,399,447, Chaloner-Gill, etal., issued Mar. 21, 1995; U.S. Pat. No. 5,411,820, Chaloner-Gill,issued May 2, 1995; U.S. Pat. No. 5,435,054, Tonder et al., issued Jul.25, 1995; U.S. Pat. No. 5,463,179, Chaloner-Gill et al., issued Oct. 31,1995; U.S. Pat. No. 5,482,795, Chaloner-Gill., issued Jan. 9, 1996; U.S.Pat. No. 5,660,948, Barker, issued Sep. 16, 1995; and U.S. Pat. No.6,306,215, Larkin, issued Oct. 23, 2001. A preferred electrolyte matrixcomprises organic polymers, including VdF:HFP. Examples of casting,lamination and formation of cells using VdF:HFP are as described in U.S.Pat. Nos. 5,418,091, Gozdz et al., issued May 23, 1995; U.S. Pat. No.5,460,904, Gozdz et al., issued Oct. 24, 1995; U.S. Pat. No. 5,456,000,Gozdz et al., issued Oct. 10, 1995; and U.S. Pat. No. 5,540,741, Gozdzet at., issued Jul. 30, 1996; all of which are incorporated by referenceherein.

The electrochemical cell architecture is typically governed by theelectrolyte phase. A liquid electrolyte battery generally has acylindrical shape, with a thick protective cover to prevent leakage ofthe internal liquid. Liquid electrolyte batteries tend to be bulkierrelative to solid electrolyte batteries due to the liquid phase andextensive sealed cover. A solid electrolyte battery, is capable ofminiaturization, and can be shaped into a thin film. This capabilityallows for a much greater flexibility when shaping the battery andconfiguring the receiving apparatus. The solid state polymer electrolytecells can form flat sheets or prismatic (rectangular) packages, whichcan be modified to fit into the existing void spaces remaining inelectronic devices during the design phase.

The following non-limiting examples illustrate the compositions andmethods of the present invention.

EXAMPLE 1

An electrode active material comprising Li₂NiPO₄F, representative of theformula Li_(1+x)NiPO₄F_(x), is made as follows. First, a LiNiPO₄precursor is made according to the following reaction scheme.0.5 Li₂CO₃+0.334 Ni₃(PO₄)₂.7H₂O+0.334 (NH₄)₂HPO₄→LiNiPO₄+2.833H₂O+0.667 NH₃+0.5 CO₂

A mixture of 36.95 g (0.5 mot) of Li₂CO₃, 164.01 (0.334 mol) ofNi₃(PO₄)_(2.7)H₂O, and 44.11 g (0.334 mol) of (NH4)₂HPO₄ is made, usinga mortar and pestle. The mixture is pelletized, and transferred to a boxoven equipped with a atmospheric air gas flow. The mixture is heated, ata ramp rate of about 2° C. minute to an ultimate temperature of about800° C., and maintained at this temperature for 16 hours. The product isthen cooled to ambient temperature (about 21° C.).

Li_(1+x)NiPO₄F_(x) is then made from the LiNiPO₄ precursor. In theExample that follows, x is 1.0, so that the active material produced isrepresented by the formula Li₂NiPO₄F. The material is made according tothe following reaction scheme.LiNiPO₄+xLiF→Li_(1+x)NiPo4F_(x)

For x equal to 1.0, a mixture of 160.85 (1 mol) LiNiPO₄ and 25.94 g (1mol) LiF is made, using a moltar and pestle. The mixture is pelletized,and transferred to a temperature-controlled tube furnace equipped with aargon gas flow. The mixture is heated at a ramp rate of about 2°/minuteto an ultimate temperature of about 850° C. The product is then cooledto ambient temperature (about 20° C.).

A cathode electrode is made comprising the Li₂NiPO₄F electrode activematerial, comprising 80% of the electrode active material; 8% Super Pcarbon; and 12% KYNAR® binder. (KYNAR® is a commercially availablePVdF:HFP copolymer used as binder material.) A battery is madecomprising the cathode, a lithium metal anode, and an electrolytecomprising a 1 molar LiPF₆ dissolved in a 2:1 weight ratio mixture of ECand DMC.

EXAMPLE 2

An electrode active material comprising Li_(1+x)CoPO₄F_(x) is made asfollows. First, a LiCoPO₄ precursor is made according to the followingreaction scheme.0.334 Li₃PO₄+0.334 CO₃(PO₄)₂.8H₂O→LiCoPO₄+2.833H₂OA mixture of 38.6 g (0.334 mol) of Li₃PO₄ and 170.29 g (0.334 mol) ofCO₃(PO₄)₂.8H₂O is made, using a mortar and pestle. The mixture ispelletized, and transferred to a box oven equipped with a atmosphere airgas flow. The mixture is heated at a ramp rate of about 2°/minute to anultimate temperature of about 800° C., and maintained at thistemperature for about 8 hours. The product is then cooled to about 25°C.

Li_(1+x)CoPO₄F_(x) is then made from the LiCoPO₄ precursor according tothe following reaction scheme.LiCoPO₄+xLiF→Li_(1+x)CoPO₄F_(x)

Illustrative for x equals 1.0, a mixture of 160.85 g (1.0 mol) ofLiCoPO₄ and 25.94 g (1.0 mol) of LiF is made using a mortar and pestle.The mixture is then pelletized, and transferred to atemperature-controlled tube furnace equipped with an argon gas flow. Themixture is heated at a ramp rate of about 2° C./minute to an ultimatetemperature of about 750° C. in the flowing argon gas atmosphere. Theproduct is then cooled to ambient temperature (about 21° C.).

EXAMPLE 3

An electrode active material comprising Li_(1+x)FePO4F_(x) is made asfollows. First, a LiFePO₄ precursor is made according to the followingreaction scheme.LiH₂PO₄+0.5 Fe₂O₃+0.5C→LiFePO₄+0.5 CO+1.0H₂O

A mixture of 103.93 (1.0 mol) of LiH₂PO₄, 79.86 g (0.5 mol) of Fe₂O₃,and 12.0 g (1.0 mol) of carbon (a 100% weight excess) is made, using amortar and pestle. The mixture is pelletized, and transferred to atemperature-controlled tube furnace equipped with a argon gas flow. Themixture is heated at a ramp rate of about 2° C./minute to an ultimatetemperature of about 750° C. in the inert atmosphere, and maintained atthis temperature for about 8 hours. The product is then cooled toambient temperature (about 20° C.).

The Li_(1+x)FePO₄F_(x) is then from the LiFePO₄ precursor according tothe following reaction scheme.LiFePO₄+xLiF→Li_(1-x)FePO₄F_(x)For the case where x=1.0, a mixture of 157.76 g (1.0 mol) of LiFePO₄ and25.94 g (1.0 mol) of LiF is made using a mortar and pestle. The mixtureis pelletized, and transferred to a temperature-controlled tube furnaceequipped with a flowing argon gas flow. The mixture is heated at a ramprate of about 2°/minute to an ultimate temperature of about 750° C. inthe inert atmosphere, and maintained at this temperature for about 8hours. The product is then cooled to ambient temperature (about 18° C.).

EXAMPLE 4

An electrode active material comprising Li_(1+x)MnPO₄F is made asfollows, specifically exemplified for x=1.0. First, a LiMnPO₄ precursoris made by the following reaction scheme.0.5Li₂CO₃+1.0 MnO+1.0 (NH₄)₂HPO₄→LiMnPO₄+2.0 NH₃+1.5H₂O+0.5 CO₂A mixture of 36.95 g (0.5 mol) of Li₂CO₃, 70.94 g (1.0 mol) of MnO, and132.06 g (1.0 mol) of (NH₄)₂HPO₄ is made, using a mortar and pestle. Themixture is pelletized, and transferred to a box oven equipped with aargon gas flow. The mixture is heated at a ramp rate of about 2°/minuteto an ultimate temperature of about 700° C. and maintained at thistemperature for about 24 hours. The product is then cooled to ambienttemperature.

The Li_(1+x)MnPO₄F. is then from the LiMnPO₄ precursor by the followingreaction scheme.LiMnPO₄+xLiF→Li_(1+x)MnPO4F_(x)For x=1.0, a mixture of 156.85 g (1.0 mol) of LiMnPO₄ and 25.94 g (1.0mol) of LiF is made using a mortar and pestle. The mixture ispelletized, and transferred to a temperature-controlled tube furnaceequipped with an argon gas flow. The mixture is heated at a ramp rate ofabout 2°/minute to an ultimate temperature of about 725° C. in the argongas atmosphere. The product is then cooled to ambient temperature.

EXAMPLE 5

An electrode active material comprising Li_(1+x)CuPO₄F_(x) is made asfollows. First, a LiCuPO₄ precursor is made by the following reactionscheme.0.5 Li₂CO₃+1.0 CuO+1.0 (NH₄)₂HPO₄→LiCuPO₄+2.0 NH₃+1.5H₂O+0.5 CO₁A mixture of 36.95 g (0.5 mot) of LiCO3, 79.95 g (1.0 mol) of CuO, and132.06 g (1.0 mol) of (NH₄)₂HPO₄ is made using a mortar and pestle. Themixture is pelletized, and transferred to a box oven equipped with anair flow. The mixture is heated at a ramp rate of about 2°/minute to anultimate temperature of about 600° maintained at this temperature forabout 8 hours. The product is then cooled to ambient temperature.

The Li_(1+x)CuPO₄F_(x) is then made from the LiCuPO₄ precursor by thefollowing reaction scheme.LiCuPO₄+xLiF→Li_(1+x)CuPO₄F_(x)Illustrating for x=1.0, a mixture of 165.46 g (1.0 mol) of LiCuPO₄ and25.94 g (1.0 mol) of LiF is made using a mortar and pestle, andpelletized. The mixture is placed inside a covered and sealed nickelcrucible and transferred to a box oven. The mixture is heated rapidly(>50° C./min) to an ultimate temperature of about 600° C. and maintainedat this temperature for about 15 minutes. The product is then cooled toambient temperature.

EXAMPLE 6

An electrode active material comprising Li₂Fe_(0.9)Mg_(0.1)PO₄F,representative of the formula A_(1+x)M′_(1-b)M′_(b)PO₄F_(x), is made asfollows. First, a LiFe_(0.9)Mg_(0.1)PO₄ precursor is made according tothe following reaction scheme.0.50 LiCO₃+0.45 Fe₂O₃+0.10 Mg(OH)₂+(NH₄)₂HPO₄+0.45C→LiFe_(0.9)Mg_(0.1)PO₄+0.50 CO₂+0.45 CO+2.0 NH₃+1.6H₂OA mixture of 36.95 g (0.50 mol) of Li₂CO₃, 71.86 g (0.45 mol) of Fe₂O₃,5.83 g (0.10 mol) of 0.10 Mg(OH)₂, 132.06 g (1.0 mol) of (NH4)₂HPO₄, and10.8 g (0.90 g-mol, 100% excess) of carbon is made, using a mortar andpestle. The mixture is pelletized, and transferred to atemperature-controlled tube furnace equipped with an argon gas flow. Themixture is heated at a ramp rate of about 2° C./minute to an ultimatetemperature of about 750° C. in the inert atmosphere and maintained atthis temperature for about 8 hours. The product is then cooled toambient temperature (about 22° C.).

The Li_(1+x)Feo_(0.9)Mg_(0.1)PO₄F is then made from theLiFe_(0.9)Mg_(0.1)PO₄ precursor, according to the following reactionscheme, where x equals 1.0.LiFe_(0.9)Mg_(0.1)PO₄+LiF→Li₂Fe_(0.9)Mg_(0.1)PO₄FA mixture of 1.082 g LiFe_(0.9)Mg_(0.1)PO₄ and 0.181 g LiF is made usinga mortar and pestle. The mixture is pelletized, placed in a covered andsealed nickel crucible, and transferred to a box oven in an inert(argon) atmosphere. The mixture is heated rapidly to an ultimatetemperature of 700° C. in the inert atmosphere, and maintained at thistemperature for about 15 minutes. The product is cooled to ambienttemperature (about 21° C.).

EXAMPLE 7

An electrode active material of formula Li₂Fe_(0.9)Mg_(0.1)PO₄F, is madeby the following alternative reaction scheme.0.5 Li₂CO₃+0.45 Fe₂O₃+0.1 Mg(OH)₂+(NH₄)₂HPO₄+0.45C+LiF→Li₂Fe_(0.9)Mg_(0.1)PO₄F+0.5CO₂+0.45CO+2NH₃+1.6H₂OIn this example, the product of Example 6 is made in a single step fromstarting materials that contain an alkali metal compound, two differentmetal sources, a phosphate compound and an alkali metal halide,exemplified by lithium fluoride. The starting materials in molar amountsas indicated in the equation are combined, mixed, and pelletized. Thesample is heated in an oven at a ramp rate of 20 per minute to anultimate temperature of 750° C. and maintained at this temperature for 8hours. At this temperature, carbon monoxide is the materialpredominantly formed from the carbon.

EXAMPLE 8

An electrode active material comprisingLi_(0.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25) is made according to the followingreaction scheme.LiFe_(0.9)Mg_(0.1)PO₄+xLiF→Li_(1+x)Fe_(0.9)Mg_(0.1)PO₄F_(x)For x equal to 0.25, 1.082 grams of LiFe_(0.9)Mg_(0.1)PO₄ (made as inExample 6) and 0.044 grams of LiF are premixed and pelletized,transferred to an oven and heated to an ultimate temperature of 700° C.and maintained for 15 minutes at this temperature. The sample is cooledand removed from the oven. Almost no weight loss is recorded for thereaction, consistent with full incorporation of the lithium fluorideinto the phosphate structure to make an active material of formulaLi_(1.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25).

EXAMPLE 9

An electrode active material comprising Na_(1.2)VPO₄F_(1.2) is made asfollows. In a first step, a metal phosphate is made by carbothermalreduction of a metal oxide, here exemplified by vanadium pentoxide. Theoverall reaction scheme of the carbothermal reduction is as follows.0.5V₂O₅+NH₄H₂PO₄+C→VPO₄+NH₃+1.5H₂O+CO31.5 grams of VPO₅, 39.35 grams of NH₄H₂PO₄ and 4.5 grams of carbon (10%excess) are used. The precursors are premixed using a mortar and pestleand then pelletized. The pellet is transferred to an oven equipped witha flowing air atmosphere. The sample is heated at a ramp rate of 20 perminute to an ultimate temperature of 300° C. and maintained at thistemperature for three hours. The sample is cooled to room temperature,removed from the oven, recovered, re-mixed and repelletized. The pelletis transferred to a furnace with an argon atmosphere. The sample isheated at a ramp rate of 20 per minute to an ultimate temperature 750°C. and maintained at this temperature for 8 hours.

In a second step, the vanadium phosphate made in the first step isreacted with an alkali metal halide, exemplified by sodium fluoride,according to the following reaction scheme.xNaF+VPO₄→Na_(x)VPO₄F_(x)5.836 grams of VPO₄ and 1.679 grams of NaF are used. The precursors arepre-mixed using a mortar and pestle and then pelletized. The pellet istransferred to an oven equipped with a flowing argon atmosphere, thesample is heated at a ramp rate of 20 per minute to an ultimatetemperature of 750° C. and maintained at this temperature for an hour.The sample is cooled and removed from the furnace.

To make Na_(1.2)VPO₄F_(1.2), the reaction is repeated with a 20% massexcess of sodium fluoride over the previous reaction. The precursors arepre-mixed using a mortar and pestle and pelletized as before. The sampleis heated to an ultimate temperature of 700° C. and maintained at thistemperature for 15 minutes. The sample is cooled and removed from theoven. There is only a small weight loss during reaction, indicatingalmost full incorporation of the NaF.

To make an active material of formula Na_(1.5)VPO4F_(1.5) the reactionis repeated with an approximate 50% mass excess of sodium fluoride overthe first reaction. The sample is heated at 700° C. for 15 minutes,cooled, and removed from the oven.

EXAMPLE 10

Electrode active materials comprising compounds of the formulaNa_(x)CrPO₄F_(x), exemplifying the general formula A_(x)MPO₄Z_(x), aremade according to the following reaction scheme.Cr₂O₃+(NH₄)₂HPO₄ +xNaF→Na_(x)CrPO₄F_(x)+2NH₃+1.5H₂OThe starting materials are mixed using a mortar and pestle palletized,placed into an oven and heated to a temperature of 800° C. andmaintained at this temperature for six hours.

EXAMPLE 11

An electrode active material comprising NaMnPO₄F is made according tothe following reaction scheme.NaF+MnPO₄2H₂O→NaMnPO₄F+2H₂OFor this reaction, the MnPO₄ may be conveniently made from Mn₂O₅ bycarbothermal reduction. 1.87 grams of MnPO₄.2H₂O and 0.419 grams of NaFare mixed, pelletized, and heated in an oven up to an ultimatetemperature of 500° C. and maintained for fifteen minutes.

EXAMPLE 12

An electrode active material comprising NaCoPO₄F is made according tothe following reaction scheme.0.33CO₃O₄+NH4H₂PO₄+NaF+0.083O₂→NaCoPO₄F+NH₃+1.5H₂OThis active material is made under oxidizing conditions where the metalin the final product has a higher oxidation state than the metal in thestarting material. 3 grams of CO₃O₄, 1.57 grams of NaF, and 4.31 gramsof NH₄H₂PO₄ are mixed, pelletized, and heated to an ultimate temperatureof 300° C. and maintained at the temperature for three hours. Thissample is cooled, removed from the oven, repelletized, and returned tothe oven where it is heated to an ultimate temperature of 800° C. andmaintained at the temperature for eight hours.

EXAMPLE 13

An electrode active material comprising Li_(0.1)Na_(0.9)VPO₄F is madeaccording to the following reaction scheme.xLiF+(1−x)NaF+VPO₄ Li_(x)Na_(1-x)VPO₄FAs an alternative to using alkaline fluorides, a reaction between VPO₄and NH₄F and a mixture of Li₂CO₃ and Na₂CO₃ may also be used.

To make Li_(0.1)Na_(0.9)VPO₄F, 1.459 grams VPO₄, 0.026 grams of LiF, and0.378 grams of NaF are premixed, pelletized, placed in an oven andheated to an ultimate temperature of 700° C. The temperature ismaintained for fifty minutes after which the sample is cooled to roomtemperature and removed from the oven. To make Li_(0.95)Na_(0.05)VPO₄F,1.459 grams of VPO₄, 0.246 grams of LiF, and 0.021 grams of NaF aremixed together and heated in an oven as in the previous step.

EXAMPLE 14

An electrode active material comprising NaVPO₄F is made hydrothermallyaccording to the following reaction scheme.NaF+VPO₄ NaVPO₄F1.49 grams of VPO₄ and 1.42 grams of NaF are premixed with approximately20 milliliters of deionized water, transferred and sealed in a ParrModel 4744 acid digestion bomb, which is a Teflon lined stainless steelhydrothermal reaction vessel. The bomb is placed in an oven and heatedat a ramp rate of 5° per minute to an ultimate temperature of 250° C. tocreate an internal pressure and maintained at this temperature forforty-eight hours. The sample is slowly cooled to room temperature andremoved from the furnace for analysis. The product sample is washedrepeatedly with deionized water to remove unreacted impurities. Then thesample is dried in an oven equipped with argon gas flow at 250° C. forone hour.

EXAMPLE 15

An electrode active material of formula NaVPO₄OH is made according tothe following alternative reaction scheme.NaOH+VPO₄ NaVPO₄OHIn this Example, the reaction of the Example 14 is repeated, except thatan appropriate molar amount of sodium hydroxide is used instead ofsodium fluoride. The reaction is carried out hydrothermally as inExample 14. The hydroxyl group is incorporated into the active materialat the relatively low temperature of reaction.

EXAMPLE 16

An electrode active material comprising NaVPO₄F is made according to thefollowing reaction scheme.0.5Na₂CO₃+NH₄F+VPO₄→NaVPO₄F+NH₃+0.5CO₂+0.5H₂O1.23 grams of VPO₄, 0.31 grams of NH₄F, and 0.45 grams Na₂CO₃ arepremixed with approximately 20 milliliters of deionized water andtransferred and sealed in a Parr Model 4744 acid digestion bomb, whichis a Teflon lined stainless steel reaction vessel. The bomb is placed inan oven and heated to an ultimate temperature of 250° C. and maintainedat this temperature for forty-eight hours. The sample is cooled to roomtemperature and removed for analysis. The sample is washed repeatedlywith the deionized water to remove unreacted impurities and thereafteris dried in an argon atmosphere at 250° C. for an hour.

EXAMPLE 17

An electrode active material comprising Li₄Fe₂(PO₄)₃F, representative ofmaterials of the general formula A^(a)M_(b)(PO₄)₃Z_(d), is madeaccording to the following reaction scheme.2 Li₂CO₃+Fe₂O₃+3NH₄H₂(PO₄)+NH4F→Li₄Fe₂(PO₄)₃F+2CO₂+4NH₃+5H₂OHere, M₂O₃ represents a +3 metal oxide or mixture of +3 metal oxides.Instead of 2 lithium carbonates, a mixture of lithium sodium andpotassium carbonates totaling two moles may be used to prepare ananalogous compound having lithium, sodium and potassium as alkalimetals. The starting material alkali metal carbonate, the metal or mixedmetal +3 oxidation state oxides, the ammonium dihydrogen phosphate, andthe ammonium fluoride are combined in stoichiometric ratios indicated inthe form of powders, and the powders are mixed and pelletized as in theprevious examples. The pellet is transferred to an oven and is heated upto an ultimate temperature of about 800° C. and maintained at thattemperature for 8 hours. The reaction mixture is then cooled and removedfrom the oven.

EXAMPLE 18

An electrode active material comprising Na₂Li₂M₂(PO₄)₃F is madeaccording to the following reaction scheme.Li₂CO₃+Na₂CO₃+2 MPO₄+NH4H₂PO₄+NH4F→Na₂Li₂M₂(PO₄)₃F+2CO₂+2NH₃+2H₂OThe starting materials are combined in the stoichiometric ratiosindicated and are reacted according to the general procedure of Example17. Here, MPO₄ represents a metal +3 phosphate or mixture of metal +3phosphates.

EXAMPLE 19

An electrode active material comprising active material Li₄V₂(PO₄)₃F,representative of materials of the general formulaA_(a)M_(b)(PO₄)₃Z_(d), is synthesized with carbothermal reductionaccording to the following reaction scheme. This reaction is based onconversion of carbon to carbon monoxide in the carbothermal reductionmechanism.2C+1.5Li₂CO₃+V₂O₅+LiF+3 NH₄H₂PO₄→Li₄V₂ (PO₄)₃F+1.5CO₂+3NH₃+4.5H₂O+2.COIn the reaction scheme, carbon is supplied in excess so that the productformed is limited by the other starting materials present. The startingmaterials are combined, mixed, pelletized, and heated according to theprocess described above in Example 7.

EXAMPLE 20

An electrode active material comprising Li₅Mn₂(PO₄)₃F₂ is made accordingto the following reaction scheme.2.5Li₂CO₃+Mn₂O₃+3 NH₄H₂PO₄+2 NH₄F→Li₅Mn₂ (PO₄)₃F₂+2.5 CO₂+5NH₃+5.5H₂O.The starting materials are combined in stoichiometric ratios asindicated and reacted under conditions similar to that of Examples 17and 18. This reaction represents the incorporation of a +4 oxidationstate metal into an active material of the invention that contains threephosphates groups. The reaction is carried out without reduction.

EXAMPLE 21

An electrode active material comprising Li₆V₂(PO₄)₃F is synthesizedaccording to the equation3C+2.5 Li₂CO₃₊V₂O₅+LiF+3NH₄H₂PO₄→Li₆V₂(PO₄)₃F+2.5CO₂+3NH₃+4.5H₂O+3CO.The equation presupposes that the carbothermal reaction proceeds withproduction of carbon monoxide. Here again, the carbon is provided inexcess, in this case to reduce the vanadium +5 species all the way downto its lowest oxidation of +2. It is appreciated in the reaction schemethat such a reduction is possible because there is enough lithium in thereaction scheme that lithium is incorporated into the reaction productin an amount sufficient to neutralize the (PO₄)₃F⁻¹⁰ group of the activematerial.

EXAMPLE 22

An electrode active material comprising Li_(1.5)Na_(1.5)M₂(PO₄)₂(PO₃F)F,where a phosphate group is partially substituted by amonofluoromonophosphate, is made as follows. This process is analogousto that described in Example 18, except that LiHPO₃F is substituted forNH₄H₂PO₄. The active material is made by the following reaction scheme:0.25 Li₂CO₃+0.75 Na₂CO₃+2 MPO₄+LiHPO₃F+NH₄F→Li_(1.5)Na_(1.5)M₂(PO₄)₂(PO₃F)F+CO₂+NH₃+H₂OThe starting materials are provided in the molar ratios indicated. Thepowdered starting materials are mixed, pelletized, and placed in an ovenat about 700° C. for 1-8 hours.

In an alternative embodiment, an extra mole of fluoride is provided sothat the reaction occurs according to the scheme:0.5 Li₂CO₃+Na₂CO₃+2 MPO₄+LiHPO₃F+2 NH₄F→Li₂Na₂M₂(PO₄)₂(PO₃F)F₂+CO₂+2 NH₃+1.5H₂OThis example demonstrates both the partial replacement of phosphate bymonofluoromonophosphate and the control of the reaction product byselection of the molar amounts of the starting materials.

EXAMPLE 23

An electrode active material comprisingNa_(0.2)LiCr(PO₄)_(0.8)(SiO₄)_(0.2)F is made according to the followingreaction scheme.Na₂CO₃+0.5 Cr₂O₃+0.8 (NH₄)₂HPO₄+LiF+0.2 SiO₂→  (a)Na_(0.2)LiCr(PO₄)_(0.8)(SiO₄)_(0.2)F+0.1 CO₂+1.6 NH₃+1.2H₂O.  (b)Powdered starting materials are provided in the molar amounts indicated,mixed, palletized, and placed in an oven. The sample is heated to anultimate temperature of 750° C. and held there for four hours.

EXAMPLE 24

An electrode active material comprising Li₄AlV(PO₄)_(2.5)(SbO₄)_(0.5)F,representative of materials of the formula A_(n)M1y⁺³ M2_(2-y) ⁺³(PO₄)_(z) (SbO₄)_(3-z)F (wherein A=Li, n=4, M1=A1, M2 V, M3=Mg, y=1, andz=2.5,) are made according to the following reaction scheme.Li₂CO₃+0.5 Al₂O₃+V PO₄+0.25 Sb₂O₅+1.5 NH H₂PO₄+NH₄F→Li₄ Al V(PO₄)_(2.5) (SbO₄)_(0.5)F+2 CO₂+2.5 NH₃+2.75H₂OPowdered starting materials are provided in the molar amounts indicated,mixed, pelletized, and placed in an oven. The sample is heated to anultimate temperature of 750° C. and held there for four hours.

EXAMPLE 25

An electrode active material comprisingLi_(2.025)CO_(0.09)A_(0.025)Mg_(0.05)PO₄ F is made as follows. (ThisExample shows the synthesis of a mixed metal active material containinglithium and three different metals, with two metals in a +2 and onemetal in a +3 oxidation state). For A =Li, a=2.025, M1=Co, M2=Al, andM3=Mg, the reaction proceeds according to the following scheme.0.5125 Li₂CO₃+0.3 CO₃(PO₄)₂.8H₂O+0.0125 Al₂O₃+0.05 Mg(OH)₂+LiF+0.4NH4H₁₂PO₄→Li_(2.025)Co_(0.9)A_(0.025)Mg_(0.05)PO₄ F+0.5125 CO₂+0.4 NH₃+8.9H₂O.Powdered starting materials are provided in the molar ratios indicated,mixed, pelletized, and heated in an oven at 750° C. for four hours toproduce a reaction product.

The examples and other embodiments described herein are exemplary andnot intended to be limiting in describing the full scope of compositionsand methods of this invention. Equivalent changes, modifications andvariations of specific embodiments, materials, compositions and methodsmay be made within the scope of the present invention, withsubstantially similar results.

1. An electrode active material represented by the general formula:A_(a)M_(b)(XY₄)₂Z_(d), wherein (a) A is selected from the groupconsisting of Li, Na, K, and mixtures thereof, and 0.1<a≦6; (b) Mcomprises one or more metals, comprising at least one metal which iscapable of undergoing oxidation to a higher valence state, and 1≦b≦3;(c) XY₄ is selected from the group consisting of X′O_(4-x)Y′_(x),X′O_(4-y) Y′_(2y), X″S₄, and mixtures thereof, where X′ is P, As, Sb,Si, Ge, S, and mixtures thereof, X″ is P, As, Sb, Si, Ge and mixturesthereof, Y′ is a halogen, 0≦x<3, and 0<y<4; and (d) Z is selected fromthe group consisting of a hydroxyl, a halogen, and mixtures thereof and0<d≦6; and wherein A, M, X, Y, Z, a, b, d, x and y are selected so as tomaintain electroneutrality of the electrode active material.
 2. Theelectrode active material according to claim 1, wherein A comprises Li.3. The electrode active material according to claim 1, wherein A is Na.4. The electrode active material according to claim 3, wherein XY₄ isPO₄ or SiO₄.
 5. The electrode active material according to claim 3,wherein XY₄ is PO₄.
 6. The electrode active material according to claim1, wherein A is Li.
 7. The electrode active material according to claim6, wherein XY₄ is PO₄ or SiO₄.
 8. The electrode active materialaccording to claim 6, wherein XY₄ is PO₄.
 9. The electrode activematerial according to claim 1, wherein a is from about 1 to about
 6. 10.The electrode active material according to claim 1, wherein M comprisesa transition metal selected from Groups 4 to 11 of the Periodic Table.11. The electrode active material according to claim 10, wherein M is a+3 oxidation state transition metal selected from Groups 4 to 11 of thePeriodic Table.
 12. The electrode active material according to claim 10,wherein M is selected from the group consisting of Fe, Co, Ni, Mn, Cu,V, Ti, Cr, and mixtures thereof.
 13. The electrode active materialaccording to claim 10, wherein XY₄ is PO₄ or SiO₄.
 14. The electrodeactive material according to claim 10, wherein XY₄ is PO₄.
 15. Theelectrode active material according to claim 1, wherein M is M′0M″,wherein M′ is at least one transition metal selected from Groups 4 to 11of the Periodic Table; and M″ is at least one element selected fromGroups 2, 3, 12, 13, and 14 of the Periodic Table.
 16. The electrodeactive material according to claim 15, wherein M′ is selected from thegroup consisting of Fe, Co, Ni, Mn, Cu, V, Ti, Cr, and mixtures thereof.17. The electrode active material according to claim 16, wherein M′ isselected from the group consisting of Fe, Co, Mn, Cu, V, Cr, andmixtures thereof.
 18. The electrode active material according to claim16, wherein M″ is selected from the group consisting of Mg, Ca, Zn, Sr,Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof.
 19. The electrode activematerial according to claim 18, wherein M″ is selected from the groupconsisting of Mg, Ca, Zn, Ba, Al, and mixtures thereof.
 20. Theelectrode active material according to claim 18, wherein XY₄ is PO₄ orSiO₄.
 21. The electrode active material according to claim 18, whereinXY₄ is PO₄.
 22. The electrode active material according to claim 15,wherein M″ is selected from the group consisting of Mg, Ca, Zn, Sr, Pb,Cd, Sn, Ba, Be, Al, and mixtures thereof.
 23. The electrode activematerial according to claim 22, wherein XY₄ is PO₄ or SiO₄.
 24. Theelectrode active material according to claim 22, wherein XY₄ is PO₄. 25.The electrode active material according to claim 1, wherein XY₄ is PO₄or SiO₄.
 26. The electrode active material according to claim 1, whereinXY₄ is PO₄.
 27. The electrode active material according to claim 1,wherein Z comprises F.
 28. The electrode active material according toclaim 1, wherein Z is selected from the group consisting of OH, F, Cl,Br, and mixtures thereof.
 29. The electrode active material according toclaim 28, wherein Z is F.
 30. The electrode active material according toclaim 28, wherein XY₄ is PO₄ or SiO₄.
 31. The electrode active materialaccording to claim 28, wherein XY₄ is PO₄.
 32. The electrode activematerial according to claim 28, wherein d is from 0.1 to about
 6. 33.The electrode active material according to claim 1, wherein d is fromabout 1 to about
 6. 34. The electrode active material according to claim1, wherein d is from about 1 to about 6.